Antenocitis workshop used to do some, but it looks like they've dropped them for their Infinity stuff.
Pig Iron do a main battle tank, but it's definitely not grav
Daemonscape do some, but I've not seen them in real life.
The Tau ones in 40k are some of my favourites, and not too 40k looking (the main thing I like about the Tau is that they're fairly generic SF figs)
Curious myself to see what others suggest