Ask HN: What problem does Foursquare/Gowalla/Places solve?

One of the most repeated advice for startups is build something people want, something that solves a problem. What problem do these services solve? They are just games/tools for sharing where I am right now. It's fun, but I can live without it. I get that there's value for business owners, but that's just a byproduct, at least I percieve it that way. For a regular user who is just checking-in, there's no real value.

So, what problem do they solve?