Well, the type of trick you want to do depends upon when you do the 180. If you throw a backroll first and then the 180, that's called a backroll to revert. Go here for instruction: http://www.kneeboardplanet.com/instruction/adv/brrevert.html
The video clip is a little old since I let go with my outside hand now. It's a little harder to hold on with one hand; however, you may find that you end up less twisted when landing.
If you throw a 180 before the backroll, that's called an invert. Go here for that instruction: http://www.kneeboardplanet.com/instruction/adv/invert.html
A Mobius(aka a Mobe) is actually any flip with a 360 degree spin thrown in, not just a 180. The Roadkill( http://www.kneeboardplanet.com/instruction/adv/roadkill.html
) is currently the only thing close. You spin 360, but there is no actual handle pass. There are a few of us determined to successfully complete a Mobe this season.