Here at the TUAW compound Quicksilver has a permanent place on our altar of 'Good Apps.' We like it, heck, we love
it! However, it isn't the most intuitive of programs.
Quicksilver has a raft of features that most people don't even know about, and triggers are one such feature (at least I didn't know about them). Luckily a great tutorial about using triggers has been written, so you'll be up to speed in no time.
What are triggers? You can assign specific key sequences, amongst other things, to 'trigger' an event on your Mac (launching a program, starting or stopping iTunes).