I was just playing around with StepBeater tonight, had it lying around for a while already. It's a very nice little stepsequencer plugin. Works great in Reaper and the most usefull feature is that when you have build a good sounding sequence or drum pattern with it, you can just drag it out of StepBeater and into a Reaper track as a midi-item.
I love this thing already after just playing with it for a little while
Added to the list in the OP.