The friends button currently doesn't do anything...  We're unsure if we're going to add any social features yet because simply sharing a location isn't really a social thing.  I mean how often would you actually use a feature like that?  We are thinking about other ways though.

One idea is like geo-tagged photos, but instead of just tagging a longitude-latitude which isn't useful at all unless you're viewing your photos on a map, it would actually tag them by the name of the place you're at and include a link to the place's page.  But this has its own problems in that it takes a long time to load the GPS indoors, more than most people are willing to wait to take a photo, and you wouldn't often take pictures outside unless you were next to a landmark or something.

Another idea is doing coupons/deals, but its not very scale-able to go around and asking all the small businesses in the US if they're interested in some kind of partnership.  And large companies and restaurant chains would be reluctant to do that unless we had tons and tons of users.

So we're still thinking of ways to expand it.  I'd love to hear of ideas if anyone can think of a way to make the app more useful (something you would realistically use all the time).