For my IRC and IM needs, I use a combination of Irssi, Bitlbee, screen and SSH. This lets me have an always on, always accessible communications platform from which to conduct my online affairs. One of the great things about using Irssi is that it is supremely scriptable using Perl. Here is a collection of some scripts I have written.

Note that none of the scripts were written 'properly'. They have all evolved to their current states by using them in live IRC environments. Therefore, they haven't been tested beyond the functionality I use, and some of the code is suboptimal or just plain not required. If you find a bug, feel free to tell me, or fix it. Whatever suits.

lookupbot.pl

Responder that uses LWP and CGI to do web scraping for various things

autoaway.pl

Simple way to automatically go /away after a time delay

megahal_irssi.pl

MegaHAL AI interface for Irssi

smackbot.pl

Smack people. That's about it.

muppet_tennis.pl

An amazing game of cannons, muppets and goo