CaptainHook is a simple plugin framework for writing Subversion hooks using .NET. This project was an internal tool by VelocIT that has been released to the community as an open source project.
SubveRSSed is a post-commit hook which builds an RSS feed and a web page from Subversion commits.
commitmessage is a Model-View-Controller framework for creating commit message processing hook scripts for CVS and Subversion.