Rock N Roller for the win. I use the 12T, all terrain, "no flat" wheels. Love it, couldn't live without it. I even keep my racks on it on stage, the wheels help with vibration issues with the dancers on the stage.
I use the Gruv V-Cart Solo, after reading about it on here from Yek. Some pics and my thoughts on it can be found here: http://forum.fractalaudio.com/lounge/87826-gruv-v-cart-solo.html#post1062057