These are the official Microsoft forums listed by site, or by forum platform. The size does not include archived forums. Add any additional forum sites that are owned by Microsoft.

Site Description Size
Web development
 62 forums
Topics: Developer, Maps, Search, and Webmaster  17 forums
Channel 9 Topics: Coffehouse (chat), Site Feedback, Tech Off, The 9 Guy Around the World, and The Sandbox  5 forums
Community/Answers  Includes Windows, Office, IE, Live, Zune, and Hotmail  9 forums with filters
Topics: GP, AX, CRM, RMS, SL, NAV, Introductions, Jobs, Feedback, and more  15 forums
Categories: Moderators, Blend, Design, Web, Encoder, Studio, Media, WPF, Feedback, and Sandbox  19 forums
Topics: Versions, General, Troubleshooting, Security, Setup, Publishing, Web Platform, and more  29 forums
Categories: Using Forums, Moderators, Learning, Dynamics, Live Mesch, Microsoft Resarch, Genuine Advantage, Academic, HPC, Windows Home Server, Windows Live, OneCare, Windows Phone, Archived, and more  112 forums
Developer/release forums
 432 forums
Office 365 Categories: Directory Integration Services, Downloads, Email, IM, Service Admin, Office Pro Plus, Web Apps, Blackberry, Upgrade, and Websites  36 forums
Topics: General, Programming, Data and Service Dev, Gaming, Mobile, Design, Other
 21 forums
Resources for IT Professionals
 432 forums
Questions about Xbox Live, games, support, Live Arcade, and more.
NOTE: This topic originated from a forum thread.