I second the vote for Resharper. It really substantially improves the quality of your code. CodeRush is also good, and more visual, either one of them is worth the money (if you can convince your employer to buy them for you :)). You would probably not want to use both at the same time, though, since there is a lot of functional overlap.
There's a cool free add-in that Scott Hanselman links to called "rockscroll", that replaces the scroll bar with a visual view of your code, I find it really helpful.
