Nice article, but I would have mentioned somewhere the COST of using the ORDER BY clause, perhaps demonstrating how SQL Server won't return any rows at all until the worktables have been built in order to enforce the ORDER BY clause.

When I demonstrate the cost of the ORDER BY clause to new developers, I often show a simple query first run w/o an ORDER BY and then adding an ORDER BY clause to demonstrate the difference in Management Studio. I think this is important for developers to understand. I've always told them to NEVER use an ORDER BY clause unless they needed server-side, ordered data becuase of the extra work SQL Server has to do in order to sort the data for you.