doniree says: They're popping up all over the place and there are all kinds of choices to consider. What do you use to check in? These are the four I'm most familiar with and benefits I think of each.
Foursquare sort of the perceived "industry leader," I chose foursquare because it seems that no matter what other service you're on, you're on 4sq. Benefits include: mayor specials (though I've never been able to unlock one), and some benefits for repeat business.
Gowalla Benefit over 4sq: photos at check-in! Downfall: not as many people use it.
Brightkite First one to market that I remember, BrightKite was also great about allowing photo uploads, but seems that this was the choice for the early adopters and has been pushed out by the new players.
Whrrl I'm still new to this one but I dig the "societies" or social groups that each checkin puts you in - great way to find what others with similar interests are also checking out near you.
