One of the best undiscovered SQL Server resource gems is the Microsoft Customer Service and Support (CSS) SQL Server Engineers blog. If you’re troubleshooting SQL Server problems, or want to learn more about the internal workings of SQL Server, the posts at this blog can help. They're provided by the CSS SQL Escalation Services team at Microsoft, who answer the phone when customers call in with problems. Here are links to the top five most interesting posts:

1. Running SQL Server in a Virtual Environment

Microsoft now supports SQL Server on Hyper-V as well as on validated Server Virtualization Validation Program configurations (which include VMware ESX Server). To learn what the CSS team will support as far as helping you run SQL Server in a virtual environment, go to the post "SQL Server Support In a Hardware Virtualization Environment."

2. Performance

Even if things are running well, performance is one of a DBA's hot buttons. To read posts about query plans, application row locking and blocking, and using per-query parallelism, click the Performance tag. 

3. Memory

Understanding how SQL Server uses memory is one of the most important steps to solving many SQL Server performance problems. For helpful posts on such topics as SQL Server 2005 memory limits (and the memory limits for the different Windows Server releases), using the SQL Server 2008 Resource Governor, and understanding working set trim problems, click the Memory tag.

4. How It Works

The How It Works tag covers a wide territory of SQL Server problems, from SQL Command mode parsing to using SQLIOSim and using DBCC Shrink. For everything you'd ever want to know about how SQL Server works, click the tag for, of course, How It Works.

5. Troubleshooting the DB Engine

When you're dealing with this core concern for all DBAs, the SQL Server Engineers Blog offers tips, workarounds for problems, information on new features, and more at the Troubleshooting the DB Engine tag.