Twit Menulet: By far the easiest and best way to stay up to date with Twitter. Scrolls tweets in the menu bar and is highly configurable, including width, font size, etc.
BOINCManager: Donates idle computer times for research of illnesses & diseases. Since it runs when your computer idles, it doesn’t affect your computing at all, but it DOES have far reaching consequences. Visit BOINC for details!
: Keeps my desktop clean, automagically.
Little Snitch: Spiffy firewall with network stats.
Camouflage: Hides desktop icons, for the times when you just want to see your wallpaper in all its glory. Easy on the eyes!
Jumpcut: Clipboard history manager.
Evernote: Don’t think this one needs an introduction :)
LogMeIn: Honestly, would love to get rid of this icon, but don’t know how to. Used to access my desktop remotely when I’m on the move.
MenuCalendarClock: More attractive and useful replacement for the standard date and time. Pops up the monthly calendar on a click. Paid version syncs with iCal as well.
Spotlight
(From Ranjit Chawla)