What is a good travel website where I can type in the departure city and leave it open for any arrival city?

I am looking to go on a last minute vacation. I don’t really care where, and my dates are flexible. I’m looking for just airfare, not a hotel-included package. I just want to know what cool last-minute deals are available out of SF. I googled “last minute” travel but none of the sites I found were good (not user friendly, and almost all included hotel costs). Any recommendations?