I think SQL is the assembly language of the data world (i.e. the wrong level of abstraction for most problems), but I really enjoy low level details about how things like SQL Server work, internally.

A few years back I read Ken Henderson's amazing, "The Guru's Guide to SQL Server Architecture and Internals" and was amazed at how much it helped me understand SQL Server and Windows in general.

This morning I found this weblog, via Jason Haley, which has bite sized (or, actually, large meal sized) chunks of SQL deep knowledge. My head hurt after the first few posts. Ouch...ouch...ouch...