Another FREE VSTi that Arman Bohn has created are this SKdrummer Synth, based on the lo-fi, 8-bit drum sounds from the infamous Casio SK-1 keyboard.
"The instrument has: Kick, Snare 1, Snare 2, Open Hat, Closed Hat, Tom 1, Tom 2, and Tom 3. Each drum has its own pitch and volume control." Via