Operations, monitoring & analytics.
Chartbeat. Chartbeat provides real-time access statistics, as well as email alerts when certain events occur, for example, when your traffic suddenly exceeds its monthly high.
Pingdom. Monitors online services availability (web, email, etc.) Sends email, SMS and twitter alerts. Can provide publicly viewable uptime reports.
Tweetoerites. Allows you to monitor the “favoriting” of your Twitter tweets.
OS X menu bar items
Adium Change status, notify on incoming messages, etc.
Dropbox In-the-cloud, file sharing.
Isolator Darkens the screen, leaving only the foreground window visible. Good for focusing on the task at hand.
iStat Menus Monitoring of CPU, memory, network usage and more.
JustNotes Simple writing environment, syncs notes to Simplenotes (so they’re available on my iPhone.)
NetworkLocation Location-aware, auto-switching of system configurations. Automatically switches a variety of settings (screen lock, etc.) when I’m at home or away.
Pastebot Provides a conduit between the clipboards of the Mac and an iPhone.
Pukka Easily send tagged bookmarks to Delicious, and search.
TextExpander. Utility to auto-expand text clippings based on shortcuts.
Tweetie Twitter client.