Today I did a conversion I had in mind for quite a while now: a Warlock Engineer with Doom Rocket! Inspired by the artwork in the Skaven Uniforms & Heraldry book I used the gunner from the Island of Blood Warpfire Thrower team, a rocket from an Ork Nobz combi-weapon, a head from the Doomwheel sprue, a Warpstone shard and small rat from the Hell Pit Abomination kit. On the back he has a bag and pistol from the Empire Pistoliers (not visible on the picture). The head is a bit big for the body but apart from that I'm quite happy with the conversion. He ranks up very well.
Oh, and what is there in the back... ?