My need is simple and commonly implemented in any location based app today, display to a user a list of all "things" in his/her area (or by a zip code / address)
Using Google Maps API (especially the new "store locator library") sounds like the safest bet, but if I would like to develop something on my own, is there a "standard" way to do so? what are the options? Yahoo geo-location API (and reverse lookup)? (Google Maps API require to use their map, not just API) purchace ZIP code files? other 3rd party services? online? offline? what is the secret?