Adium (free) - multi-protocol chat client
NetNewsWire (free with ads, or $14.95) - RSS reader that syncs with Google
Google Quick Search Box (free) - QuickSilver is dead. Long live QSB!
TextMate (30 day trial, €39) - the best, last text/code editor you'll need (unless you're one of those emacs freaks
)
The Unarchiver (free) - expands dozens of compressed formats
GlimmerBlocker (free) - easy to use local web proxy, great for blocking ads and modifying web pages
ClickToFlash (free) - require click before loading Flash objects, but with optional whitelist
Cyberduck (free) - excellent FTP/SFTP/WebDAV client with a terrifyingly bad icon (
excellent replacement icon here)
Chromium (free) - Nightly builds of Google Chrome. It's like Safari but with more features!
Flip4Mac (free player) - for the rare/occasional need to view Windows Media files
Perian (free) - QuickTime component that adds support for many more file formats and codecs
RipIt (30 day trial, $19.95) - easily rip DVDs
HandBrake (free) - convert ripped DVDs or other video files to MPEG-4 with tons of options
Plex (free) - Media center app. One day when I build a hackintosh and hook it up to my TV, it'll be running Plex.
MenuMeters (free) - adds CPU/memory/network/disk monitoring to the menu bar
Little Snitch (3-hour trial, $29.95) - out-bound firewall and network monitor, useful to see if apps are "phoning home"
Alarm Clock 2 (free) - unobtrusive alarm clock that uses iTunes and increasing volume