The whole reason I wanted to start developing on Google App Engine was because I wanted to start building a repository of code samples, How-To's, documentation, projects, blog posts, all that stuff. Something akin to Confluence. Google already did it for me.
Google just recently launched Google Sites, which basically becomes a content management system for whatever you like. It's exactly what I needed - and I'm planning on moving my docs, code snippets and projects over soon.