midi analyser ?

I don't know of a plugin available which will analyze and generate variations based on the analization, but I do know of a suite of midi plugins that will analyze and allow you to make changes based on mathmatical modeled parameters that you select.

http://www.midi-plugins.de/

If you're looking for inspiration for drum tracks, take a look at Jamstix. It's a drum sample player (with good samples, too) unlike no other, in that it will jam with you as you play, either against MIDI or audio, in a variety of styles. You can either capture what it plays as a MIDI track or just use it in real time for developing ideas.