Screensaver that changes colour based on the hex value of the current time.
A natural language calculator/scratch-pad thingy.
Bookmarked because I'm always forgetting how to do this.
Rules and evidence based context-aware computing for Mac OS X. Switch printers, network connections, drive mounts and more automatically.
Fluid CSS, a TextMate bundle for converting pixels values to ems for given font sizes. Brilliant.
A database and preference pane of hidden settings.