I organized and participate in an intercambio here at my university in the usa. Our group presently consists of 6 spaniards (exchange students studying here for a semester) and 4 americans. It has been absolutely amazing!!! We meet twice a week, sometimes just in a cafe to talk, other times we go places on or close to campus...we alternate speaking both in english and spanish. I think we have learned a lot from them as they have from us. There is never a lack of topics, and it is very relaxed. I would definitely suggest forming a group like this, I think you will find it well worth the effort. I know that next semester while I am studying in at La Universidad de Granada, I will definitely try to find a group like this to participate in!
Kelly