If you're not aware of it, Loki is one of the more interesting developments in local search. It's a downloadable toolbar from Skyhook Wireless, which initially launched in April, 2006 and has recently been upgraded. (The technology actually works on any WiFi-enabled device.) Once on a browser, it automatically determines user location by triangulating WiFi access points rather than GPS, which isn't on all devices.
Once installed, the user doesn't need to enter location into sites and applications. Those apps automatically show the relevant location when called up; this means the relevant city for Citysearch or Yahoo! Local or Fandango for movie tickets.
On one level Loki is a kind of a local "metasearch" engine, aggregating local content and tools in a single place. It embeds a range of local search engines, content and related tools to make it easier to conduct local searches from the toolbar. And there are a range of third-party extensions and add-ons, among them weather, movies, restaurant guides, real estate information, local news, store finder and numerous others.
Beyond making local search more usable, the most interesting implication of Loki is what Ted Morgan, CEO of Skyhook Wireless, calls "location pull." For example, if a retailer like Target tapped into this technology (assuming it's installed on a user's device) then, reading user location, Target could automatically offer a locally customized version of its site for that individual, including deals, the weekly circular, etc. Online newspapers, rather than asking for registrations, could offer a "national" or a "local" version of their sites accordingly. And clearly search engine (and potentially display) advertising would benefit from the greater location precision.
Loki offers an API for third-party developers and is also a Firefox add-on.