Personal -- Personal organisers
Servers -- MS-Exchange-style groupware servers for desktop clients
ProjectBased -- Project-based organisation software
BugTracking -- Issue tracking
General -- Complete groupware solutions
CRM -- Customer relationship management
CMS -- Content management for websites
Local -- My notes on groupware systems
Calendar -- Shared calendars
GrantBow - the definitive review section
Another list of groupware products, including the proprietry ones
