EVERY site should have a single sentence (at the least) with a concise, non-jargony explanation of what it is. You can't just assume.
When I saw someone mention the Favicon I went back and got it :) I think the problem I really had was that I read your "example" but it made no sense since I couldn't see any of the character boxes until I typed in the number of characters.
"Crosstips helps you finish that crossword you're stuck on."
"Need help with your crossword?"
"Can't solve a tough crossword? We're here to help..."
These aren't very good, but at least I know what the site is for now...having a description will also help with SEO.
I wouldn't want to see a slogan every time I visited the site, anyways.
Change the tip word daily to mix it up a bit.