Playing with the keys while I was using Quicksilver, some clever behaviour came to the surface. If you navigate with Quicksilver inside a folder using Command-A, you'll pick all the items inside that folder. Then just hit the Return key, and all the selected files will be open in their respective applications.
I think this tip is specially useful with folders with internet bookmarks. But as you can see, it is not the only thing you can do...
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050214141217782