I bought a Motobecane Outcast 29er from Bikesdirect a few months ago... and have been commuting on it and slowly customizing it since. It's got almost 600 miles on it total, some of which are offroading miles. I ride it on the fixed side of the hub, I haven't ever used the freewheel it came with.
Mods/addons are:
-Planet Bike fenders, with custom made aluminum stays. (The original ones wibbled too much)
-Custom built aluminum rear rack (Tested to 220 pounds so far)
-dropped the 42t chainring, replaced with a Blackspire aluminum 34t chainring for the hills
-mounted bar ends inside the grips (until I break down and buy a set of H bars, though the bar ends are very comfy)
-lights, panniers, clipless pedals, so on so forth...
And I need to wash the poor thing someday, but now it looks well loved!