Rex is a regular expression library which implements most of the POSIX 1003.2 specification. It is very mature and has been in heavy production use by thousands of users, on many platforms, since 2002.
Webstensible is an extensible application layer for building robust, web-based business applications. The framework is written in DotNet. All components are loaded via reflection and designed to be replaced to match ever-changing business requirements.
A program designed to walk the Windows registry and match keys, values, and data with regular expressions. Matched items can be deleted or the branch they are on can be pruned to a particular depth.