PDC 2005 Videos Available
For all who missed it (like me), you can now see all the 2005 PDC sessions. They're available here: https://microsoft.sitestream.com/PDC05/
Usually these are available for a while (but not indefinitely), so grab 'em while they're hot.
Obviously i think you should check out the Linq videos, but i also recommend the Monad video.
Cheers!