For a web app I'm working on, I need to know the lat/lon of about 300 US cities. I also need to know the lat/lon for every US zip code.
Does anyone know of a free source to get this information?
Freebase will likely be able to help you. Here is New York and it has Lat/Long.
The Wal-Mart Expansion video used Freebase to get it's data, and it sounds like you're doing something similar.