So many times I'm writing a query, and I think "I want to put this into that project…", but because I didn't add it when I first made the query it's a pain (and I end up copying the text into a new query).
But in SSMS 2008, I've just noticed the File menu has a "Move <file> into project" entry down near the bottom. So now I can just choose that and my query magically appears in the project. Terrific!
There seems to be so many nice little things in SSMS 2008 – try right-clicking on some data in the results grid, and you'll see "Copy with Headers". Really useful! I recommend grabbing SSMS 2008 and using it whenever you would've normally used SSMS 2005.