This smart playlist is limited to songs I've rated highly, listened to fifty times or more, but not heard in almost a year. One of my Mac OS X User Tips on Flickr.
My most frequently-clicked bookmark is probably a bookmarklet. When my browser windows start to drift across the screen, I hit this little button (•) and my window jumps back in line.
This simple Automator workflow applies the magic of tags to your own documents in the Finder. Save this as an application to enable drag and drop tagging, or as a plug-in for right-click tagging. Tags you give to files and folders are immediately accessible to Spotlight searches. Nifty!