If you've got an iPad or a Mac of any sort, you can simply record and loop a region in GarageBand. I've been doing a lot of recording for our band recently and stumbled across this use almost accidentally when I was working out a backing for a verse section in a song. You also get to see a visual representation and can adjust the region on the software. You also have a variety of in-built "drummers" or you can create your own drum parts.
