Discover Significant Developer Improvements in SharePoint Services
https://msdn.microsoft.com/msdnmag/issues/06/07/WSS30Preview/default.aspx
While a bit dated, I found this to be a great article that helps explains customized and uncustomized pages and how the spvirtualproviderpath in WSS 3.0 pulls data from SQL.
Thanks Ted Patison for the article!