LINQ to SQL on MSDN by ThinqLinq

While I was away on vacation, Wriju posted a good list of MSDN documents he calls the "LINQ to SQL Missing Manual". It is a good list and addresses a number of items people regularly ask about concerning LINQ. Perhaps the most important ones are:

• Customizing Insert, Update, and Delete Operations (LINQ to SQL)
  Describes how to add validation code and other customizations.
• Data Retrieval and CUD Operations in N-Tier Applications (LINQ to SQL)
  Provides detailed information for multi-tier applications that use LINQ to SQL.
• Object Identity (LINQ to SQL)
  Describes object identity in the LINQ to SQL object model, and explains how this feature differs from object identity in a database.

There are a bunch of other topics over there. If you are using LINQ to SQL, you should definately check it out.