If you're using Quicksilver, you won't need this much, except occasionally
when Quicksilver quits unexpectedly.
To open a file or start an application, you may be tempted to hit
the enter key. Sadly, this would let you modify the application/file
name instead of starting or opening it.
To open a file or launch an application in Finder, you can either hit
apple - O or apple - down arrow.
What if you want to open a file using some other application other than
the default? See the related post: The QuickSilver Files: Grabbing the Universe