I have been a fan of the German company Tobsen77's stuff for a year or so now, but have never bought any. I thought I would show you what they have, because if you have not found it, you need to. This stuff is definitetly on the Christmas list for me.
Blimp (does not come with gunner)
The blimp is a realtively new addition to the Tobsen line. I think it looks great, but would be really best for maybe use with 15mm, where it will seem that much larger and more impressive. You could probably fit multiple crew on it. Or maybe even in 6mm, you could have a large deck crew in the gondola. That might be awesome.
Monowheel (gunner and MG seperate, from Brigade Games, IIRC)
I have long been a fan of this monowheel model, but never been quite sure how to deploy it. I am thinking it may need to be a development of Doctor Maton's mad genius. In that case, I can fit it with the Masked Minion gun team pictured below. A little adjustment of the gunner's legs and all should be well... I have also considered using a British crewman as suggested by Tobsen, or even a German one... not sure which to go.
Masked Minion MG Team (Parroom Station, for sale through Brigade Games)
The Bismatron, a colossus of the battlefield...
Last for this post, but not least, is the new Bismatron (new to me, at least). It's huge and it has big guns and it wears a pickelhaube. The Kaiser needs one. Badly.