Mac OS X only: If Quicksilver ain't your cup of tea but you want a quick and easy way to create keyboard shortcuts for certain tasks on your Mac, Spark's for you. Map common actions (like launching applications, playing iTunes playlists, running AppleScript) to key combinations of your choice in Spark. You can even organise your shortcuts into groups and install plug-ins (like this clipboard cleaner) in Spark. Spark 3.0 is in beta, and it's a free download for Mac only. Thanks fatherfork and Jeremy!