A good free text editor : Syn
A good free text editor (my favorite) : Pspad
A free diff for Windows : CSDiff
A free file find & replace : Handy File Find and Replace
Install easily PHP, Apache & MySQL on Windows : EasyPHP
A good bug tracking system : phpBugTracker
Free programming resources : thefreecountry
Misc.
Discover Linux without any installation on your hard disk :
Knoppix
Discover the universe without a space ship :
celestia
Discover Paris without a car : Paris by bike