What are some good housewarming gift ideas?

I have two good friends who just recently got married, and are now making the move to Alaska. I would like to send them something sweet and useful. One of them is moving from Honolulu, so I thought it would be funny to order a heated mattress pad or something like that. Any other ideas? I’m just a lowly grad student, so it can’t be something extravagant like a wine club. ;-)