I have some advice that may be somewhat counterintuitive, and won't be useful for everyone, depending on your own indiviudal coping style. However, one thing that helped me through this situation was to assume a rejection if I hadn't heard from a site that had already sent out invites to others. There are certianly sites that send out rolling invites, so it's possible that they just haven't gotten all the way down the list yet - especially if it's still early in the application season! In my case, though, I was just getting my hopes up over sites that did eventually get around to sending out rejections, but often not until a few more weeks had passed. For me, it was ultimately easier to assume that no news = bad news.
