One of the pains of working with Visual Studio is that the Solution Explorer, in a large project, is hard to use. As you open more and more files, it gets harder to navigate in the solution explorer since it opens all the projects for you.
Edwin Evans wrote a nice short macro to collapse all the projects. It works with both 2003 and 2005.
Assign it to a button your toolbar and give it the smiley face icon. 'Cuz that's what you'll do when you use it.