Found this great looking add-in from a Microsoft employee Mikhail Arkhipov that allows you to do Spell Check within your code in Visual Studio 2008.  For anyone that does a lot of web development or just wanting to be able to do a spell check of your comments this would be a great add-in to have.

He provides two versions of the add-in.  One for Visual Studio 2005 and one for Visual Studio 2008 so that it is not necessary to be running the latest version to have this add-in.  I see that it is at version 2.1 complete with some bug fixes and updates since the initial release of about a week ago.

Spell Checker Add-in for Visual Studio