Ask HN: Hacking each others Apps / Websites?

Inspired by Google's Vulnerability Reward Program, I have been getting more and more interested in security and ensuring that my applications aren't open to attack. I have a feeling that there are a lot of easy wins that many new websites, applications and startups forget about in the rush to launch.. I thought it would be fun to have a group of trusted people that get together (probably virtually on skype?) and try and poke holes in each others applications to find CSRF / CS Scripting / SQL Injection and other common vulnerabilities for the benefit of all. I am just putting this out there to gauge the interest before organising anything...