Occasionally I dropped a DVD-rip into a website project, then carelessly git commit -a -m ..., and, zap, the repo was bloated by 2.2 gigs. Next time I made some edits, deleted the video file, and commited everything, but the compressed file is still there in the repository, in history.

Lightbeam is a Firefox add-on that enables you to see the first and third party sites you interact with on the Web. Using interactive visualizations, Lightbeam shows you the relationships between these third parties and the sites you visit.