Check out this groovy, lil' oldskool website, with *loads* of flash-based virtual drum machines, dating back to the early 70's! The author, a Mr. Joseph Rivers, clearly put in a loads of effort sampling the sounds and recreating the interfaces in flash. Some of these instruments are actually quite playable, while others, particularly older/rarer models, have only the sounds and presets!

Okay, time to go dialup a foxtrot, bossanova or teen beat preset and rockout! haha!