A list of sites for AD Best Pracitces at the The Sean Blog.

Best Practice Guide for Securing Windows Server Active Directory Installations Best Practice Guide for Securing Active Directory Installations and Day-to-Day Operations: Part 1 Best Practice Guide for Securing Active Directory Installations and Day-to-Day Operations: Part 2 Windows Server 2003 Deployment Kit: Designing and Deploying Directory and Security Services Windows Server 2003 Security Guide Windows Server 2008 Security Guide Achieving Autonomy and Isolation with Forests, Domains, and Organizational Units Active Directory Security Technical Implementation Guide (Non-Microsoft Guide) http://iase.disa.mil/stigs/stig/active-directory-stig-v1r1.pdf