Skyscanner.com has been doing this for a few years for european flights. It looks like they've expanded into the US and have also de-centralized this feature of

Skyscanner.com has been doing this for a few years for european flights. It looks like they've expanded into the US and have also de-centralized this feature of their website: http://www.skyscanner.com/news/articles/2010/06/006690-search-tips-and-tools---everywhere.html http://www.skyscanner.com/news/articles/2010/06/006690-searc... When I lived in Germany, I used to plug in a month, see the cheapest flights, and just go somewhere for the weekend.