Pragmatic Works (for BI) , Cuppa Corner from SQLServerFAQ are my favourites, as well as community webcasts from Quest and Redgate.
Most of the free stuff simply gets you going. It isn't rocket science, it just saves you an hour or so reading (another manual). Ramesh Meyyappan's SQLWorkshops site is different.
The videos are still FREE , But they are 'Level 400' (from attending conferences I know this to mean 'the clever stuff'! ) Anyway, if you're interested in performance monitoring and tuning you can download them from http://www.sqlworkshops.com/
Ramesh Meyyappan attended SQLBits V where I saw him present his 'Let's make SQL fly' talk.
After presenting 'Monitoring & Tuning Parallel Query Execution' at SQLBits VI he is back for more on October 2nd to present 'Monitoring & Tuning Parallel Query Execution - Part II at SQLBits VII
* (yes I was encouraged to write this post due to a potential freebie t-shirt, but I do genuinely rate the webcasts)