Here's one I did in Bushrat's sketchbook at FC 2006. Somehow I lost the thing for a full year, only finding it again this week. Now, convention pics are good for when I just can't think of something new to draw, so I colored it.

Bushrat here wanted a pic of him riding a falan. I explained that putting him on the back of a falan in battle dress didn't make much sense, but he insisted he wanted to be drawn operating a crew served weapon on its back. Note the distant falan with a similar cannon without the rat operator. 83