Here is a list of sites that are known to use BrowserID for sign-ins.
- Haskellers: meeting place for professional Haskell developers
- Libravatar: Open Source federated avatar hosting
- My Favorite Beer: official BrowserID demo
- Open Photo: Open Source photo sharing
- Munchy Lunchy: Munchy Lunchy reservation site
- Tools Atto: A personal site in Belgium
- Richard Milewski blog: A personal site in US
- 5apps News Community-edited news aggregator for HTML5/JS/etc
And a couple public libraries for using BrowserID:
(list moved to https://github.com/mozilla/browserid/wiki/Persona-Libraries)