- The least lame Twitter client I’ve tried.
 - Recently been trying out this slick little IMAP email client.
Dropbox (Flash Drives have now joined Floppy Disk and Zip Disk in the retirement home.)
Utility for the scanner function on the Canon MG5220 Multifunction machine. I actually use Image Capture to actually scan, but it breaks if I remove this.
controller - The device itself was designed for video editing, but I use it for brush resizing and zooming in/out in Photoshop and Illustrator. Buttons are mapped to key modifiers. (Way better than Express Keys on my Wacom Tablet.
 - Necessity when working on multiple devices.
Jumpcut - Multi-item clipboard utility. Only handles text, but does it well.
Transmit - Nice FTP/S3 transfers
iChat, MenuMeters, Time Machine, Blutetooth, AirPort Signal, Keyboard/Character Viewer (for when I can’t remember how to type certain oddball characters), Media Eject, Clock, and Spotlight, which I pretty much use as an app launcher.
(From Mike Shoaf)