TWiki
I maintain a TWiki installation on this site. A TWiki is an implementation of wiki, which is a website that enables users to edit its content right through the browser. TWiki offers more security than traditional wikis, which appealed to me since my earlier installations of other kinds of wikis resulted in a lot of spam on the site. TWiki, a PERL-based application, allows for user accounts and access controls on the page level.
TWiki is a convenient and highly-customizable application for working with collaborative documents in a hurry when security is an issue and layout and presentation is not. Some of the projects that have used this site include the academic honesty policy drafted by the Ad Hoc Committee on Student Plagiarism at UMass Amherst and the UMass Amherst Writing Program's Teacher Resource Web (login required -- drop me an email if you'd like to have a look). The Basic Writing course director group at UMass Amherst and the Writing Center have also used the TWiki for collaboration.
I've also posted there a working copy of the Writing Center Tutoring Database I designed in MS Access 2003 to track student usage of the Center. This version does not have the reporting functions, but I'll have that version posted soon.