Having a need for a small-business groupware solution (specifically for project management, task management and possibly timesheeting, issue tracking) I started to poke around to see what's around.
My preference is ASP, SQL based.
 
Here's a shortlist:
 
*Stylite Egroupware
http://www.egroupware.org/Home
-New release Oct 2008
-PHP under IIS (XAMP recommended) http://www.egroupware.org/index.php?page_name=dependencies&lang=&wikipage=php
-MySQL5 (MSSQL "sort of works"
-Free - vendor sells managed, hosted services
-Windows Mobile vis Synthesis client via SyncML
-Features: http://www.stylite.de/EGroupware_functions
Good task management and tracking, calendaring, contacts (not sure about how well Outlook/Windows Mobile sync works), web-based file manager (not quite Document Management but is WebDAV enabled) 
Knowledge management (articles etc), resource bookings (cars etc), timesheets linkable to anything on the server, 

*Redmine
http://www.redmine.org/
-Under regular development
-Deployment tips here - http://fluxqubit.wordpress.com/2008/08/22/the-absolute-all-in-one-project-managment-tool-redmine-extensive-howto/
-Ruby 2.12, MySQL >4.1 (eg http://rubyinstaller.rubyforge.org/wiki/wiki.pl) http://mirrors.ntua.gr/MySQL/Downloads/MySQL-5.0/
-Not particularly Windows/IIS friendly
Gantt charts, Doc and file management, feeds and email notifications, Per-project wiki and forums, time tracking, custom fields for timetracking/issues/projects
Subprojects, Flexible issue tracking. HTML or text view.

*Sharpforge
https://sharpforge.org/p/SharpForge.aspx
-Targeted at software development but is applicable to other uses
-Still in beta, kind of active development but slow
-FOSS, C#, .Net 2.0, SQL2005Ex+, IIS, 
-Aims to be a sourceforge replacement
-Not a particularly intuitive product for project management

*OpenGoo
http://www.opengoo.org/
-Seems to be more of a web based office package
Reasonable task management with time tracking

*Project.Net
http://www.project.net/
-LAMP/WiMP (PHP/MySQL)
-Moderate ongoing development - new release July 2008
-Used by deBortoli Wines
-Focused on Project Management
Email ticketing, Client/Company management, project listings, hierachical task lists, File repository, Calendar, Forums, ACLs

*ProjectCompanion
http://www.projectcompanion.com/products.asp
-IIS4+, .Net1.1+, SQL2000 or SQL2005Ex
-Free version, not fully featured but still very useful ($80 per user standard)
-Project management, Action management, Project diary, document management
-Licensed versions add project portfolio, time/expenses, workflow . Enterprise == nvoicing, sales/profitability reports, business trend analysis, other features
Very good, focused project management - great UI.
Enterprise Features are strong, could replace an accounting system? But price unknown. http://www.projectcompanion.com/enterprise/