We've moved our Top Projects page to the wiki so anyone can add/edit it. Feel free to add things to the list that you want. This is a good place for Zimlet ideas or integration with external services or other OSS projects.
We've also applied to be part of Google's Summer of code. If we are accepted this list will help students focus ideas and get a feel for what type of projects the Zimbra community is interested in.
If your a student interested in getting paid to work on Zimbra this summer please PM me and I'll add you to the list of folks we notify if/when we are accepted.