I haven't seen this being shared yet on TL, but this is something great that caught my eye on reddit. Some guy named Masterguide on reddit made these unbelievably good wallpapers.
To view them check these links:
Zerg: http://imgur.com/a/g3zHG
Protoss : http://imgur.com/a/TBgtc
Terran: http://imgur.com/a/7f4f9
To download:
Zerg+Protoss: http://nannal.com/sc2/All.zip
Zerg: http://nannal.com/sc2/Zerg.zip
Protoss: http://nannal.com/sc2/Protoss.zip
Terran: Sorry but you'll have to download them individually from http://imgur.com/a/7f4f9 until somebody uploads a pack
To be honest, I prefer the protoss wallpapers to the zerg ones, but that maybe just me. Zealot and colossi wallpapers are pure win. However, they're all so awesome that I have about 15 of them as my wallpaper on auto-rotate.
He is going to release a series with terran units soon, so I will try and update this thread when that comes out.
All credits go to masterguide on reddit.
original protoss thread on reddit
original zerg thread on reddit
original terran thread on reddit
Enjoy! =)