As an owner of the Vita I will say that the share thing is really only cool for specific games. Also, I guess if you really want to Co-op with people, you can see which games are popular in your area.
Disgaea 3 is one of the games that is awesome with Share. The further you travel (and not play the game), the higher your Honour Quotient gets. Which lets you gain more exp, sell items for more while buying them for cheaper, etc. etc.