These are mostly MSDN, but they cover some of the most common questions that I get:
- Making custom renderer for reporting service
http://msdn.microsoft.com/msdnmag/issues/05/02/CustomRenderers/default.aspx - Single Sign-on MSDN style
http://weblogs.asp.net/hernandl/archive/2004/06/09/ssoformsauth.aspx - Signle Sign-on Vasalek style
http://www.codeproject.com/aspnet/aspnetsinglesignon.asp - Sitemap Provider
http://msdn2.microsoft.com/En-US/library/aa479033.aspx - Another MSDN sitemap provider article
http://msdn2.microsoft.com/en-us/library/aa479320.aspx - Membership Providers
http://msdn2.microsoft.com/en-us/library/aa479031.aspx - Customizing your Membership Provider
http://msdn2.microsoft.com/en-us/library/aa479046.aspx - Role Providers
http://msdn2.microsoft.com/en-us/library/aa479032.aspx - Profile Provider
http://msdn2.microsoft.com/en-us/library/aa479035.aspx - Custom provider services. Includes some of the links above.
http://msdn2.microsoft.com/en-us/library/aa479038.aspx - Custom Page state persister
http://msdn2.microsoft.com/en-us/library/aa479403.aspx - User less code to secure your app
http://msdn2.microsoft.com/en-us/library/aa479008.aspx - Anti-Cross site scripting lib
http://msdn2.microsoft.com/en-us/library/aa973813.aspx