Temporary Link

Auto-It - Simple program creates scripts for mouse to move and click on its own

Check Links - Removes dead links for files & shortcuts that no longer exist

CkRename - Awesome little number for renaming many files at once

CleanUp40 - Great program for cleaning up your computer safely

Duplicate - Searches multiple folders/drives for identical files by name, size, CRC

Folding@Home - fold proteins on your PC to help cure cancer & Alzheimer's disease.

Hijack This - Lists programs that run at startup - use with care - creates logs too

Hover IP - Ping IPs, show your IP or IPs assigned to network adapters

RegSeeker - Best tool I've come across for cleaning up your registry

SpybotSD - SpyBot Search and Destroy - finds and fixes adware and malware

Startup Control Panel - simply uncheck programs to NOT start up with windows

StrokeIt - not what you're thinking... add mouse gestures to windows environment

Teamspeak Client - Talk with family over the computer like your phone - yes, it's free

Tweak User Interface - for XP only - make lots of small changes to windows

Western Digital Hard Drive Diagnostics for Windows

What's Running - A process explorer to reveal good and evil apps running 

Wizmo - neat little file with many uses - take a look at the link - no install required

               Folding At Home