I read (and thoroughly enjoyed) LINQ in Action a couple of months ago and find myself constantly referring back to it.

Most people seem to immediately assume that LINQ is just LINQ to SQL, which means they either immediately love it or hate it. This is a shame because LINQ is so much more and regardless of your thoughts on LINQ to SQL, LINQ is a tool that once understood will change how you write code (in a very good way).

If you have not had a chance to really experiment with LINQ yet, I highly recommend checking out LINQ in Action (Official book site).