This thread reminds me of the cacophony of similar questions people had about Twitter when it was the center of attention. I think the problems that these location apps solve are quite obvious, just like I thought that Twitter very obviously solved problems too.

The catch is, however, that you need to have a significant amount of your friends and acquaintances using either service for them to become useful. Imagine if you were in college, and were meeting a bunch of new people every week, and you could see at any moment where your new friends are hanging out, or partying, or studying. You could see where the most popular hangouts are. You could check and see if anyone you know is at the same location you are currently at.

Once the network effect kicks in, these apps become awesome. And yes, just as people pigeonholed Twitter as being a narcissistic service, these apps allow people to express themselves as well, only through their choice of venue, not their choice of words.

If you want practical solutions, imagine a street team for a band or product going around town hitting all the hip locations spreading the word about a new album or product. They could keep tabs on each other as they fan out over the city and make sure they don't double up on locations.

The possibilities are endless, really. You just need to use your imagination and stop being so skeptical.