I have of late been watching the Q's, an ETF for the NASDAQ 100. They are trading near some low support and did not get a boost from the Fannie/Freddie buyout. However, their Implied Volatility is still relatively low at about 25%. And, there is always a lot of volume.
I have been watching VXN to see if it gives me buy and sell signals for the NASDAQ 100 and QQQQ, before I jump in with long calls or puts.
The other thing to watch is the double Q's QLD. They mimic the price movement of the Q's roughly 200%. Every price swing up or down it's done two fold. Because of those larger price swings, they also have twice the implied volatility at 56%. However, there isn't nearly as much Put/Call volume on the QLD's as the Q's.
This is just on my watch list. I'm watching the volatility smile to see where the money goes, and I am testing this system to see if it is going to work.