I use a good ole Roland R-5...I got it in 1989 and I've used it consistently to practice with (and occasionally record with) ever since.
One cool thing you can do to practice chops and timing with a d.m.: find the writing mode on your device, come up with some time signature, then randomly add bass drum and snare throughout the blank slots...play it back and try to nail the accents and groove on it for a while until the random/bizarro resultant rhythm starts sounding smooth and second nature. Then, delete it all and do it again with some other time signature.
Now that's what they call good clean fun.
[PS. I'm convinced this is how some Meshuggah and Soilent Green songs are originated....]
(Message edited by eligilam on June 05, 2010)