I know there are plenty of books that show you maps of zip codes. We had to use those when we were sending invitations for our wedding. Try amazon or your local book store for those.
As for websites, I did a search and it came up with this site:
http://www.zip-codes.com/
It says you have to download it, but on the right side of the page there is a spot where you can put a city and get the zip, area code, county, and state for each city. I tried it on a couple of cities I knew the zip code on and it worked. Just one problem, if you want a map I believe your have to download it for a price.