Well, there's Asgarrd, which seems to mostly have a friendly relationship with Earth. Thor is on the network, he seems like a nice enough chap. But the main contact that everyone knows about was the battle here in New York a few years back - before the refugees started arriving. When some of us first came in there was still rebuilding happening. It's less noticeable now, but a lot of midtown was destroyed in the fall-out. google search the Battle of New York and it'll give you a good look into the history.