I really like the help files generated using SandCastle on my projects... is there a plugin for Visual Studio 2010 for SandCastle, or another good alternative program that integrates directly with Visual Studio?
SHFB has a VS2010 extension - available in the 1.9.3.4 (beta 2) release. You will need to check subsequent releases to make sure those continue to include the extension.
http://shfb.codeplex.com/releases
and details here - http://www.ewoodruff.us/shfbdocs/Index.aspx?topic=html/b128ad2a-787e-48c7-b946-f6953080c386.htm