3g video-calls

It depends on the network, obviously. They're not particularly expensive, but it's not something to do on a daily basis. It's just a fun way to communicate with friends. The sound isn't especially good, nor is the picture. It's a novelty, and it's still pretty much underdeveloped, although it's advanced enough.

It's quite useful actually, in many cases the price is the same as a voice call, but it depends on the network.