How to use arduino uno with the computer?

I just bought an UNO. I dont have a bread board or any components just a UNO. There's not much i can do with just that. I want to know if i can use it with computer application like make it into a keylogger or something like a facebook notification app. I know i can do this with just programming but will it be possible to this kind of stuff with an Arduino?

Yes you can use it with your computer, i would also look into Processing for that

but the Arduino is more for interfacing Software with the real world , so lets say you make an application that notifies your arduino when you have a message or comment etc.. with nothing connected to it, not even an LED then its really pointless if you ask me, if all its doing is telling you something that you HAVE to be at your computer to see and since your there then why not just open up a browser page and log into your facebook.

Without and hardware the arduuino is just a low powered computer that you can communicate with using the serial monitor. So if you want to run any of those 70s style text based programs then you can. However there is not much point.
Get some LEDs (and resistors) and start them flashing.

Yea thats what i plan to do when i get some money. But for right now all i got is the arduino. And until i get a bread board and some stuff i cant do much. My first app will be just to make the onboard led blink when i have a new email or facebook notification. I might bike to the nearest radio shack but only have about 6 bucks. What should i get?

Go to, for $4 and $2 in shipping you can get a bunch of resisters, LEDs, other stuff.

Will i be able to make little projects like that before i get anything? Like a facebook app that blinks the onboard led when i got a notification or something?

Yeah, that you can do. D13 is an onboard LED that you can make blink.
If you can download the Blink sketch, it will blink, and you can start experimenting with responding to inputs received via the Serial interface

Once you have the IDE installed, you can click on File:Examples: and poke around, see what code looks like.
Try some and Serial.print stuff from the PC USB port and send stuff back:

//define the variables
byte inByte = 0;  //variable are Case Sensitive - make sure names called out all match
// define the pins to use
byte LEDPin = 13;
void setup(){
Serial.begin (9600);  // turns on Serial IO library - set up IDE Serial Monitor to match
pinMode (LEDPin, OUTPUT);  // so we can write out & see something
} // end of setup
void loop()
  // if the uC UART has valid byte:
  if (Serial.available() > 0) {
    // then we can read it:
    inByte =;
// and send it back
// or send it back with a line feed (carriage return)
}  // end of if
else {
// blink the LED
digitalWrite(LEDPin, HIGH);
delay (25);  // make longer if flash is too brief - slows down response time too next character coming in tho
digitalWrite (LEDPin, LOW);
} // end of else
}  // end of void loop

How t get facebook to send something out serial port? I don't know.

Have you got a wire coat hanger, or some other stiff wire? If so you can make a steady hands game. Connect the wire to an input, enable the pull up resistors. Connect a loop of wire in a wand to ground and try and guid the loop through the wire without touching it.
Then you can add extra input wires at each end and time how long it takes to get from one end to the other.