From your bio description, I'd place you in the 'beginner' category, more than the 'intermediate'. Just for reference.
As a beginner I got a lot of milage out of Toby Teorey's "Database Modeling & Design", which is still the one I throw at friends when they start on databases. It's fairly light, too, so when I throw it they don't get hurt. Fast read, too.
Teorey is published by Morgan Kaufmann, which I think makes the best DB books hands down. They also publish a book on representing temporal data in SQL databases that is hands-down amazing. I'll find the box I packed it in and get the name off that soon.
I disagree with Arjun that the best way to learn is just to read well-regarded data models. Data models themselves are not fantastically descriptive to novices, nor do they educate well. Continue to learn formally about design while taking that route. Props on the Celko book, though.
