The Expertiza project is software to create reusable learning objects through peer review. It also supports team projects, and the submission of almost any document type, including URLs and wiki pages.
Spamato is a spam filter system that combines several anti-spam techniques, from which thousands of users benefit. It is available as an add-on for Thunderbird and Outlook, and as a stand-alone proxy for other email clients. IMAP and POP are supported.