To add to what logical said. Hashes are used very extensively outside of just storing passwords. One major place, that you've probably seen, is in file verification. When you download a file, it will often have a hash associated with it. To make there were no problems with the file download you can hash the file and compare it to the known hash of the file. If those two match, then the file is intact, if not, you should download it again. This is also done on a lower level. I'm not completely sure ATM but I think it's layer 2 of the OSI model that computes a CRC(a type of hash) on the incoming packets to check if there were any problems.
Probably one of the largest areas hashes are used is in database search optimization. Hashes can be used to make searching through a database much faster. I don't think google publishes it method for searching it's databases but you can be sure it's a very complex situation involving hashes. This is a very large(and very interesting) subject, so I'll just leave it at that.


