Magento

Hey guys,

I’m looking for an extension that takes a zip code and finds the closest city.  I have magento setup with multiple stores that are different cities, hopefully I can attach a zip code to that city or can magento do that out of the box?  I would like it to also add a cookie so you can visit the site again with out entering in the same information.

You can see examples when you first land on groupon and living social.

Is there any kind of module or extension for this?