We're hoping to release a new version of DrProject next week, and persuade some Trac users to upgrade. (Multiple projects! Mailing lists! Role-based access control! Scripting interface!) This is therefore a good time to take a fresh look at what other systems offer:
SourceForge: not the first web-based software project portal, but certainly the best known and (probably) the most widely used; not free, and too big for most student projects and startups (though there are lots of cases of both using it).
Google Code: much smaller, but growing fast; only available as a hosted service (which rules it out for course projects in many jurisdictions, and for companies that want to keep their software behind their firewall).
Trac: probably the most popular entry-level open source system; this is what we forked DrProject from, and what we're hoping to supercede.
Mingle: a relatively new offering from ThoughtWorks specifically aimed at agile projects (and lovers of sticky notes everywhere). Very attractive, but not open.
Rally, VersionOne, ScrumWorks, TargetProcess, and Acunote: same story as Mingle.
OpenProj: an open source alternative to Microsoft Project, available both on the desktop and as a service.
XPlanner, ExtremePlanner, ProjectCards, XPStoryStudio, PlanningPoker, and Plan B: all target agile processes, but lack some or all of the features of an all-purpose portal.
Perforce: my favorite version control system, which also has simple task management, but not the rest of the features a team needs in a portal.
ClearCase: a configuration management tool rather than a portal; definitely not something to inflict on a small team (or a large one, for that matter).
Jazz: "an IBM Rational project to build a scalable, extensible team collaboration platform for integrating work across the phases of the development lifecycle." Slightly smaller than Greenland, and not yet finished; definitely not for student teams.
So, what have I missed?