Directory Opus: My favorite file manager.
Billy: A very lightweight no-nonsense music player.
Macro Express: I use this mainly to auto click on program controls like 'I agree'..sort of like 'Push That Freaking Button'.
Direct Folders: I use it to quickly jump to frequently used folders and for the 'click switch' feature.
Browser Tray Switch: I want to set Firefox as default browser while at home and IE while at work. I use BTS for this.
StrokeIt: For mouse gestures.
PhraseExpress: One of the most useful software I've ever used.
ClipX: My favorite clipboard manager. Clipboard menu has 2nd item highlighted by default and that's excellent thinking w.r.t usability on part of the creator.
Find And Run Robot: What I like about this is the advanced features like aliases and plugins. But when it comes to raw speed, my ex launcher, Executor is awesome.
AutoHotKey script: This is a simple one in which I have set hotkeys for common programs like Word, Outlook, IE..