I'm rather partial to Bork'an's scheme. It's not hard to do it looking somewhat beat-up, and it gives me an excuse to combine a couple of techniques on basing.
White primer. Codex gray basecoat. Thinned chaos black wash to bring out the lines. Drybrush armor with fortress gray, skull white. Sept markings in hawk turqoise, then ice blue. Rifle in black.
Base: texturing with thin layer of Squadron Green Putty, scuffed up w/ toothpick. Paint brown, then wash w/ devlan mud. Snow from this interesting tutorial with found items.
White primer. Basecoat in codex gray. Base armor in ultramarines blue. Drybrush armor w/ fortress gray, then ice blue. Wash model in thinned-down black. Gun in black, sept markings in orange.
White primer. Wash cloth with thinned chaos black, drybrush with skull white. Base armor in brown, then wash with devlan mud. Black gun, sept markings as Bork'an.
Cities of Death-esque Tau
White primer. Red gore cloth, codex gray armor. Muted with thinned chaos black. Drybrush armor, gun w/ fortress gray, lighter drybrush on higher areas w/ skull white.
I believe I've found my scheme for my Tau, and the mud/snow base helps the scheme pop.
The pictures would show the more textured look of the Bork'an armor, save that the camera's got no zoom. My girlfriend loaned it to me, then got a better one for her birthday, so for the time being I get a 'free' camera. (Olympus D360L, dunked in water a few times, dropped a few times, but STILL going.)