A couple of days ago, I came across this fine paper by Keir Mierle et al. from U of Toronto:
Mining Student CVS Repositories for Performance Indicators
They examined the CVS repositories that their students used for assignments
Every SourceForge project has a statistics page with the number of daily page views and downloads (example). Last year, I built a little screenscraper (page in German) that converted any project’s stats page into an RSS feed. But earlier this year