You can margin trade on BTC-e as well.
Considering BTCE's liquidity, I would highly advise against that. MT4 and BTCE are notorious for flash crashes into thin books. It would be very easy to lose everything on a price spike that doesn't happen on any of the other exchanges. For this reason, I mostly use my funds on BTCE to trade unleveraged, and keep very low bids all the time to catch any flash crash.