Believe it or not, 15 minutes ago I was thinking "hey, it's a while that Dan don't change it's avatar" and here it is.
Are the glasses a new trend or your sight has dropped a bit?
Your discovery is pretty neat. There's a plethora of DM to try with. I've also found this one
http://www.rinki.net/pekka/monkey/# which is fun because you can actually program it. For every drum sample you choose when it should play in the loop and if with full or half strenght. Pretty raw but easy to use. You can also export your beat pattern to share it.
The problem is that I have no clue about rhythm so no drum machines look helpful for now.