I've been reading about, studying, and using LINQ to SQL for a couple months now and after all this time I somehow never ran across this MSDN web page.
101 LINQ Samples - VB Version (has lots more content and sections on LINQ to SQL, etc)
After just a few minutes of digging through it's samples, I've already learned more than I care to admit. These samples help to show that LINQ is a lot deeper and more expressive than you might think at first glance.
[Update: 10-26]
After some additional searches and aimless browsing on the MSDN site I discovered there are multiple flavors and versions of the "101 LINQ Samples". I've updated the links above to include what I think are the most current pages.
Here are some other links to similar "101 LINQ Samples" pages that I think are out of date but may still have nuggets of value buried in them:
101 LINQ to Entities Samples - Downloadable Zip from the ADO.Net Team (out-of-date)
LINQ Samples from Orcas March CTP - Another Downloadable Zip (out-of-date)
LINQ and language samples for Visual Studio 2008 Beta 2 - Executable samples package from here