Netpro is offering a free ebook on Active Directory Troubleshooting in Adobe Acrobat (PDF) format. You'll have to register however. They don't use it to bombard you with sales calls or product literature. And the only times they've emailed me were to notify me about a new ebook that they are offering, which doesn't happen very often. Bindview is offering a similar deal for an ebook on Windows 2000 Security 
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