This One is for the Propeller Heads

If you're looking for Open Source Software, check out the Patent Cafe's OSS Patent Search Engine. Registration is required and you'll need to read the info and make your own decision as to how you wish to register. Here is how the site describes itself.

"PatentCafe's exclusive OSS Patent Search Engine™ contains only Open Source Software (OSS) patents that patent owners have made available to software developers. The initial collection includes IBM's 500 Open Source Software Patents. It is the only free, natural language patent search engine for software developers interested in utilizing OSS patents."