Where can I go to learn how to read a sql server execution plan?

I'm looking for resources that can teach me how to properly read a sql server execution plan.

I'm a long time developer, with tons of sql server experience, but I've never really learned how to really understand what an execution plan is saying to me.

I guess I'm looking for links, books, anything that can describe things like whether a clustered index scan is good or bad along with examples on how to fix issues.

From serverfault Chris Lively

• I've heard good things about SQL Server 2008 Query Performance Tuning Distilled. I haven't read it yet myself but it's on my own to buy list. Lots of great reviews for it on Amazon, blogs, etc...

  From Dynamo

• I think this free e-book from Grant Fitchey is a really good place to start. I'm not shilling for RedGate, trust me, just recommending a good freebie. Use the "Just the E-book please" link to skip the trial software.

  Other than that, the SQL 2008 Internals book from Kalen Delaney/Tripp/Randall is a bit more all-encompassing, but excellent

  From SqlACID