Type Quicksilver os x into google and it'll appear as a hit.
The best way is to run it and you can then see how useful it is (I personally consider it essential---computers just seem broken without it).
Also, go to
iusethis mac software: New Releases
it's a database of progs used by the mac community. It's rated and added to by us users (rather than developers) so gives a good idea of what's good and what alternatives there are.
.....have fun
