I’ve been using Quicksilver for a few months now. It was one of the first applications I loaded onto my laptop when I first bought it. I use Quicksilver as an application launcher mostly because I can’t remember all the key commands to execute the other amazing things it can do.
Lifehacker put together a list of the Top 10 plugins for Quicksilver.
I’ve started using QS to launch specific bookmarks with FireFox. This basically opens up FireFox and launches a bookmark at the same time. Not staggeringly productive, but it probably shaves a few keystrokes from the whole mess.
I tried opening music with iTunes this way, but I think I like the process of browsing my playlists for whatever suits my mood.
