The [http://www.mozilla.org/projects/calendar/ Calendar project] has lots of stuff for people to do, from [http://www.microsoft.com/exchange/default.mspx Exchange] connectors to off-line caching to bug fixes and minor features galore. A good place to start is the #calendar IRC channel on moznet.

It would be great to store Firefox's saved passwords in the [http://en.wikipedia.org/wiki/Apple_Keychain OS X keychain], for consistency and ease of use.