Caffeine (control whether or not your computer can go to sleep in one click)
aMSN (Better version of MSN. Webcams, Nudges, Winks ect...)
Skype (Awesome for chatting, video conferences, Screen sharing ect...)
Zattoo (Watch live TV for free. UK only at the moment)
MPEG Streamcip (Great for editing, downloading and CONVERTING videos)
Blender (3D vector creation)
DoubleTwist (An iTunes for phones and other devices that can't connect to iTunes)
Handbrake (DVD ripper)
FunBooth (Like a really fun photobooth)
Img2Icns (Easy conversion of images to icons)
iStat Server (Lets you see everthing about your mac. Check out the widget to)
NameChanger (easy way to change names of loads of photo's for example)
Senuti (Put content from your iPod/iPhone on your computer)
smcFanControl (Control your fans RPM. Great for laptops if they're getting to hot)
VirtualBox (Run other OS's without reboot. Like a free Parrallels)
Sorry there's no links...