Vimeo member Switch Flick uses pieces from a Flycam Nano to make a DIY Spidertrax Rotating Dolly. Axles are a bit long on this first version, but it looks pretty legit with attention to details down to the bolts (much like I used in my setup). Of course, this is all assuming you've already dished out a bit of change for the Nano.
If you're not familiar with the Flycam Nano, another video was recently shot using a Canon 5D Mark II + 17-40mm F/4L + Rode Video Mic. That's quite a bit of weight, but Vimeo member Spencer Turley managed to pull off some great footage while doing some charitable work out in Tuvalu. Found here: http://www.vimeo.com/20742652
If you're not familiar with Rotating Dollies, you can see how the Konova Dolly (cloned after my own design) was used in this video: http://cheesycam.com/test-drive-spidertrax-clone-korean-dolly/