Did you know that the HP theme park has an Owlery? Here is a blurb from their Muggle-site: The Owl Post itself is a functioning postal office. You can drop your letters and postcards into the post box, and they will be delivered with an authentic Hogsmeade postmark.
What fun! Cant get to Florida? They offer an e-owl as well. I sent one to myself, to see what it would look like. Here is what came to tell me I had an owl:
This is what appeared when I clicked on it (what Muggles come up with!):
A great way for your HH students to communicate with each other over the summer; in addition to having them write letters, of course.