There's lots of cheap casio keyboards that you can program beats and chords into. Some of em sound pretty cool too. I jam with mine all the time.
If you're keyboard is midi there are lots of midi editing programs online that you can also program stuff into. There's the ol band in a box program too, I was never a big fan of that though. Had it many years ago and never really used it. I'm sure it's changed unbelievably since then however.