Skipfish is this Google code project created by Michal Zalewski. This prject is a web application security scanner. Its amazing!

Here is there brief overview:

Skipfish is an active web application security reconnaissance tool. It prepares an interactive sitemap for the targeted site by carrying out a recursive crawl and dictionary-based probes. The resulting map is then annotated with the output from a number of active (but hopefully non-disruptive) security checks. The final report generated by the tool is meant to serve as a foundation for professional web application security assessments.

Talk about easy to use! This program rocks! It has helped so much in my project development making sure that all the apps we produce are secure and safe from the worlds hackers! It is one of my right arms in development there is no doubt. Highly recommend to download and use if your a developer! Here is the link: http://code.google.com/p/skipfish/