Guess I will add my most used apps
Ibackup - Backup program for osx will backup settings from just about any application along with specified folders and system settings.
Unison - Usenet application
Auction Hunter - ebay search and snipe program
Skype - if you use skype for PC its the same for osx
Firefox - Dont ask me why I dont use safari I dont know I guess i am a sucker for that "cool" firefox logo.
Mactracker - neat but sometimes useless application for osx will tell you everything you ever wanted to know about any mac product ever made.
Shape shifter-great for changing the osx GUI look
Garage sale- the mac equivilent of turbo lister if you ever used turbo lister you know its crap and crashes every 5 seconds use garagesale and you will never go back
I'll post more if i can think of them