I think there is no such thing as a group finder. Still you should be able to communicate to people close to the quests you are going to start with. Normally some of them are up for it too, don't you think? Therefore it shouldn't be a problem to find mates in Guild Wars 2 that will get on quests with you. But of a certain system I have never heard :l Maybe you will find some help on the internet. I found this page for example: http://www.gamebandits.com/ps3/guild-wars-2/1325/. Perhaps you find something on there, not sure though!