If the OP wants to compare options based on how much premium is attributable to time without also considering Implied Volatility, then Theta is the best measure. Otherwise, (as you mentioned) you can simply look at the price of the options and strip out any intrinsic value. But since the OP stated that he was looking for something different than what is provided by Yahoo, I'm guessing that he is trying to discover theta.
Doesn't appear to be any options on futures data (e.g. ES, NQ, YM, etc.) and since I only trade the ES (E-mini S&P 500) options I rarely go to the NASDAQ site. Clunky site in any case but thanks for pointing that out. Best