Alright, cheap airline tickets seems like an oxymoron these days.  I've tried all the websites (Kayak, cheaptickets, lastminutetravel, orbitz, priceline, etc, etc, etc)

What sites do you use to find great travel deals? 

Also, I am looking for "last minute" type websites for great travel deals.  I would like to take some weekend trips to San Francisco, Boston, San Diego, etc.