Loki for Mozilla Firefox or IE
Be prepared to be offended (or entertained) by some channels, such as the one that shows nearby strip clubs for both men and women. And I found that channel information isn't always particularly useful --- for example, the restaurants channel showed me restaurants from miles away rather than those nearby. Still, the channels are of some use.
Loki Toolbar also functions as a social networking tool, because you can choose to have your location shown to others, and see the location of others, so that you can connect in the real world if you'd like.
--Preston Gralla Note: This download will take you to the developer's site.