Whether you moved forward with the idea or abandoned it, I'd love to hear some of your thoughts and reasoning (rather than a plethora of yes/no responses).
PriceAdvance.com is a YC interview reject from Fall 07. We went to our interview with a prototype. After the rejection call, we had a few beers and discussed next steps. We started development the following week and launched about 2 months later. Our application recently passed 250K downloads and has received a decent amount of press. We are now covering monthly expenses and should be profitable soon.