I'll give this a shot. We used to use google latitude to good effect, but it didn't survive.

I like that it tries to use a ad hoc mesh network as sometimes the crowd kills the cell network. One hopes its good on batteries.

It's pretty decent on batteries. It only wakes up when a friend is actively searching for you, and only for ~4 seconds.

Nice tool, is there a way to have a compass / direction arrow pointed at the direction of your nearby friend?

that's a good idea. I'll try to add something like that to the next release.

In the current version, you can tap the navigate icon on the top-right of the map and the map will rotate to follow your heading. Then you can just point it towards any of your friends. But you're right, a simple compass could be better.