Sublime text 2, best text editor for web development imo since textmate is dead in the water. Best of all you purchase one license and you can install it on any computer no matter the os. I have it on my mac, win 7, and linux machines. It is written in python so it is not for the feint of heart especially if you are looking to add plugins and mods.
TextExpanderfor OSX only unfortunately =(. Easy to record text macros so you don't have to keep retyping shit.
Cygwin on windows cause PUTTY just doesn't cut it.
VMWare and Oracle VirtualBox.
Spotify, duh! And it's available on win, linux, and osx.
Daemontools lite, for mounting iso's. Small install and easy to use.
Kingsoft office writer. For those too cheap to pony up for MS Office this is a pretty decent free alternative.
Hydra IRC client. It's a
freeIRC client for windows. Best of all no fucking adds or annoying messages when you leave a room.
Teamviewer. For when you need to remote to another computer pc or mac in a hurry. Free as well
Media Player Classiceasy to use for watching most video formats.