Since Scoble asked and everyone posted their list of favorite apps, here’s my list:
QuickSilver (which I can’t live without), TextExpander, Adium, iGTD, iTerm, Firefox, TextMate, Yojimbo, Parallels, NetNewsWire, MarsEdit, Default Folder X, Growl, ChronoSync, Fetch, Google Notifier, Graphic Converter, Stuffit Deluxe, Twitterific, VLC, Delicious Library.
