Pidgin (chatting application, I use it for MSN/AIM)
X-chat (another chatting application, IRC this time(the BEST irc client imo))
Firefox (with adblock & some other essential addons... please, for the love of god, don't use internet explorer! It's the best way to get your computer raped by malware.. basically about as awesome as bending over arse-naked in prison)
K-Lite codec pack (including Media Player Classic)
Winamp + VolumeLogic plugin (VolumeLogic was an awesome audio plugin made by plantronics, it makes your music sound so much better. Unfortunately they stopped making it, but the old version I have still works for winamp

)
uTorrent/Newsleecher (I use my laptop as a low-power 24/7 platform for downloading and chat-logging so I can turn my beast of a desktop off and save money on power)
Notepad++ (much better than standard notepad)
Netstumbler (gotta catch em all... (the wifi APs))
CCleaner (keeps it nice and tidy)
Auslogics Disk Defrag (A nice light/free defragger that I believe works better than most everything else, even the paid softwares)
Games (emulators+roms but also small games like Peggle, bejeweled, etc)