A pack of monsters would be really sweet, just stuff like Devilsaurs, raptors, crocolisks, birds, cats, wolves, just bunch of sweet mosnters and animals, because most of those could fit in really well with other Starcraft 2 models.
I think there is a problem with creating your own skins using the DEV software. I started with a human. Put Clothes on him and weapons. After getting him set up the way I wanted him to look to export him I updated the export options then I exported to an M3 file. After doing this I imported into SC2. From here all of the cloths and Items were jumbled around.