What's your opinion about this wifi module?
http://www.ebay.es/itm/WiFi-Module-Shield-for-Arduino-Connect-UART-WiFi-module-with-Arduino-easily-/130721771260?pt=LH_DefaultDomain_0&hash=item1e6f9feefc
It´s a TLG10UA03
More information here
Did you notice that the offer you linked to does not include the WiFi module but only the adapter shield?
OK, sorry
This module Rock by the way. Only problem, it as to be alimented from outside. The Arduino offer 50mA on 3,3 volt and the TLG10UA03 need 300mA on 3,3volt. That's why the linking shield has a external plug to hook it on outside alimentation.
But it's great. If you know how to handle AT command, it's just as flexible as the official shield, except that it communicate with Arduino using USART serial port instead of the SPI port.
TCP IP stacking is built in, and it can be configure from AT command or there is an AUTO mode that can be configure from a web page contained in the module.
A different, and less expensive approach:-
Use a standard ethernet shield, or module, together with a TP-Link WR702N Nano in Client mode. This will convert your wired connection to wireless painlessly.
You could then just set up your server using the numerous examples available for ethernet.
Use standard ethernet library (Ethernet.h) for W5100 based and UIP Ethernet librsry (UIPEthernet.h) for ENC28J60 based.
The sketch code is identical for both libraries. You can thus switch device types by simply changing the #include for the library. This also allows you to develop on an Arduino + W5100 based shield and easily swap to an ENC28J60 module for any final discrete build.
n theory I would agree with you as long your project is supposed ton sit on a table and has a power supply hooked on the wall.
Personally, I prefers this little module, that is about the size of a finger. I don't use it with the shield so it's very very space wise.
Other thing, you can eazely adapt the WiFi or Ethernet library to work it with the module, since in many way the TLG work the same way except for the fact that it communicate with Arduino using the serial port. So basically you adapt it to send the same stuff but Serial way.
The ENC28J60 is totally off subject since there is not TCPIP stacking built in so let's just pass that part, it's gonna require half of you Arduino programming space just for the external stacking.
But what I really like about the TLG unit, is that in fact it does not even need a Ardunio to work. I've tried to hook a GPS, a Bluetooth module, a external US Robotic Modem using a RS232 to ttl module, and many other serial device on the TLG serial port, and they all worked fine sending and receiving there stuff on the net. It's completely stand alone, the fact that Arduino can use it, is just a plus.
In fact, it even has a GPIO programmable from the network using telnet or locally sending AT command in the serial port. It's as simple to use then saying ATA to a modem when the phone ring.
So by the end, a simple web server saying Hello World take about 3k of program space. It require only 2 wires to communicate with Arduino AND considering the GPIO, you can say that you gain back one of the two wires on the TLG device side.
I'm the kind of guy who prefers module over shield, especially because I can choose what i can hook where. And to me this module is way way better the any shield I've tried so far.
Finally this module alone cost about 14$, compare to a minimum of 10$ for the W5100 shield + i don't know how much for the TP-Link WR702N Nano , but it has to be less then 6$ to beat the TLG unit.
20 buck on amazon, Nah, not worth it Sorry
For the WR702N plus the W5100 shield, I get 2 TLG unit an extra module of my choice, all that shipping included.
So i might conclude by saying for those who prefer shield that the adapter shield is 15$, the TLG module is usually around 14$ So for the same price you have the TLG set(shield + module). But to me because the TLG unit is so stand alone, you get more for your money with the TLG option. You will learn more, and Have more fun.
But, if your the Mac kinda persone, and you just want to hook and look at it work, with out work, go for the W5100, it's ease to use all is ready and there is no challenge, but also nothing to learn.
I'm the PC kinda guy, I like to build program and learn stuff. Every one is different.
By the way, I've learn a interesting fact.
This example is the generic example that come with the module in automatic mode( the server is preconfigure on on the config web page of the TLG unit has a TCP host on some port you choose)
void setup()
{
Serial.begin(115200);
}
void loop()
{
boolean currentLineIsBlank = true;
while(1){
if (Serial.available()) {
char c = Serial.read();
// if you've gotten to the end of the line (received a newline
// character) and the line is blank, the http request has ended,
// so you can send a reply
if (c == 'n' && currentLineIsBlank) {
// send the webpage
Serial.println("HTTP/1.1 200 OKrnContent-Type: text/htmlrnrn<center><h1>Hello World!! I am WiFi WebServer!!!</h1></center>");
break;
}
if (c == 'n') {
// you're starting a new line
currentLineIsBlank = true;
}
else if (c != 'r') {
// you've gotten a character on the current line
currentLineIsBlank = false;
}
}
}
}
If you use a Méga256, and if you have not update the boot loader, this line will cause fault when you upload you sketch
Serial.println("HTTP/1.1 200 OKrnContent-Type: text/htmlrnrn<center><h1>Hello World!! I am WiFi WebServer!!!</h1>
Just remove 1 of the "!" in the string cause there seem to be a bug in the original boot loader, it does not accept "!!!" in a string.
Have you got a link to that module @ $14? I may have to go get one to have a play. 
lol
Check on ali that were i got mine.
I payd like 12 buck but the lady ran out, I know there are some at 14 that have see today
Tcheck for UART WIFI. they will come up
tiens
Jane @ Freezone is cool i often deal with her, never any problem.
Thanks for that Frederic. I have just ordered 2 to play with. 
Go to the second link that pepemanuer left, well there basicaly:
Cause the documentation is full a cool details, and you got lot of reading a head of you. There are about 30 AT command to read about, very very configuable using the AT command.
You got lot of fun coming up, i'm happy for you.
May I suggest you get your self a terminal software to test some AT command "script" you could wish to try, By experience, it's messy to upload to the Arduino to see if a series of command does what you want to do.
Personally I like to use this guy:
http://realterm.sourceforge.net/
For this and many other serial need. It's full a neat stuff integrated to the terminal.
Hey Tack! Got your modules yet?
Hi Frederic, I would like to be able to control my Arduino over wifi, ie digital pins ie.
Is the module from aliexpress all I need? I would prefer not to mess with spacious shields etc. Is there a way to connect it or do I need a shield? Do you have any schematics?
Thank you
Nick
Well if you only need to control some ports, like turning on and off a few relay, for example, yes this module will do the job with eaze. Once you have configure the device to connect it on your wifi hub or configure it to host an adhoc connection, it become just like a serial over tcpip bridge, well that is what it is any way.
So what i'm saying is any serial example you can find in the IDE will work. Except that you will need to use a telnet client, instead of a serial terminal, to access it. Unless you setup a second tlg device to hook on your computer serial port. Then it would be completely transparent and then you could use a serial terminal. So basicaly with one tlg device you use telnet, with two you use serial terminal.
But in bolth case, you need to have some understanding of AT command. But honestly it's pretty much like setting up a bluetooth connection. The only thing is that there is lot more AT commands. Some will say that it give more flexibility, other will say it is more complicated. In any case, once the connection is setup, it become just like any serial connection on the point of vue of Arduino.
hi I have baught this module . but when I connect it through usb-ttl ,it does not recognize the port. I have unchecked the auto mode from browser. bt still it is not being connected by usb.please help
Hello Saki
Can you be more specific, what terminal software are you using for your testing? Is hook on the Arduino? Are you using AT command for testing? Tel me what you have done so far. And can you join a picture of your instalation? And please tel me you are powering the module with 3.3volt.
We will make it work, dont worry
Frederic thank you very much.
I've made a heating controller to control my boiler and monitor some temp/humidity sensors, co sensor, fuel tank level via an ultrasonic sensor and have some buttons on a keypad like ECO mode, HOME/AWAY, change temp setpoint etc.
So what I want to do wirelessly is first of all turn on/off boiler and waterpump, change the setpoint temperature and maybe have a look at the boiler temps and ground/1st floor temps. All of these via wifi.
Can you please point a cheap wifi module to do that? Is this ok?
http://www.ebay.com/itm/NRF24L01-2-4Ghz-Wireless-Transceiver-Module-for-PIC-Arduino-Raspberry-Pi-/360771028888?pt=UK_Computing_Other_Computing_Networking&hash=item53ffa10798
Many thanks
Nick
NRF24 module are neat, not expensive little module that does the job very well for sending command over a certain distance. But, altouth they also work at 2,4GHZ, they do not use the same procedure then a wifi network to do the job. But, many very interesting project of home automation use these modules.
So if what you want to do is plain home automation, without controling it over the net, they could do the job, other ways, you would need a bridge, maybe in form of a NRF24 usb modules that is hook on your computer, that host a server, or an Arduino that has a internet connection and a NRF24 module that run a server to bridge bolth world.
Ider way it's possible and doable.
Thanks, I'll give it a try.. What is the maximum distance the NRF24 will cope? Also I guess it can accept commands via android right?
Otherwise which module would you recommend?