Here's a project requiring minimal hardware to implement a basic RC5 IR remote: just an Arduino, battery and IR LED:

Here's a link to a zip file containing the code (rc5xmit.pde and irparams.h):
http://wikiputer.org/arduino/rc5xmit.zipThe code as it stands just has a demo program in the main loop to do some basic operations on a TV. It shows how the code is pretty straightforward to use:
Code:brand(PHILIPSTV) ;
button(POWER,2) ; // hello world
delay(15000) ;
button(ZERO,2) ; // change channel to 03
delay(100) ;
button(THREE,2) ;
delay(100) ;
button(MUTE,2) ; // mute the TV
delay(15000) ;
button(POWER,2) ; // over and out
Of course, this works only with some TV models, and the code may have to be changed to accomodate other RC5 devices.