How is the effect called when you slap a drum stick on the metal edge of the snare?
It's known as a side-stick or cross-stick
Google found this http://freewavesamples.com/side-stick
or this set looks pretty comprehensive - http://www.freesound.org/people/quartertone/packs/8839/
I didn't test either of the above, I've got more drum samples here than I really know what to do with ;)