I already read some websites/modules for arduino and the availablity of wifi, gprs, mifare and lcd.
My question is, can I cascade them all into one single system? Does anybody already created this combination? I really like to discuss about the howto.
I don't know of any such combination that is already available. The problem with cascading them is that they might require the same interface resources. For example a Mifare module usually communicates with a serial port as does a GPRS so it's not straight forward to have them on the same system. Yes there are ways round this like using a soft serial port but it needs doing and the software needs hacking to suite. Things sharing the I2C bus usually present no problem because the bus was designed to have several devices on it. LCD character displays are normally a "set and forget" interface but sometimes, especially with graphics displays they require multiplexing and so that steels some time from the processor.
Finally there is the issue of code space, it is limited especially the amount of RAM you have. All these interfaces take up resources and you might not have enough free to actually do your application when it is all loaded in.
I've a similar problem, I want connect Arduino with 3 serial devices.
I ordered an 328P to enlarge capacity and I will use soft serial port.
I hope that's possible.
Maybe another solution is to use Sanguino (2 serial ports)