I was wondering if I could learn ASP.net or other web programming frameworks by studying existing functional open source apps of the simpler kind. As in, of not quite MediaWiki complexity and so forth. Perhaps something like "simple forum" or "simple web store". Something that is non-trivial and demonstrating useful functionality, but not overly complex and afflicted with hard to understand feature bloat.
So, could people suggest some apps of this kind for study? Does anybody know let's say of some straigtforward forum app in ASP.net that would be a good learning tool for an experienced programmer with minimal web app exposure? Or likewise of good open source apps for study of PHP, JavaEE and/or other popular web frameworks?