I'm looking for a track system for videos and time-lapse videos. What I've seen so far that looks good is the Phillip Bloom's Pocket Dolly, but they seem to be sold out. It does sound like what I need, so what are the other options?

My Needs:
Hold a GH2 camera or Nikon D90 with (sometimes heavy) lens, video head,etc attached (etc may be a mic or a flash...). I'm smart enough to balance the system so that it doesn't tip over.
Small enough for easy 1 man transport.
Able to attach a motor (suggestions on that one?) so I can do variable speed and repeatable glides.
Mountable to a tripod at one end or along the track, also able to be stationed on the ground with feet.
Able to glide vertically, horizontally, and upside-down. Basically any orientation I may require. For the shot.
Water proof (aka water doesn't case it an issue, yes without a motor attached).

Thanks

G

check out Dynamic Perception LLC, Open-Source TimeLapse Motion Control Systems (http://dynamicperception.com)