What should I give my boyfriend as a going away present to remind him of me?

My boyfriend and I have been together for 2 1/2 months, but we had been close friends for the 3 months preceding that and friends for 4 months before that, since we met at the start of college. He just got a job to spend 2 months sailing in the Mediterranean (I know - completely awesome job!), during which time we'll have basically no contact; because he'll be living on a sailboat, he won't really have internet service either. I'm stuck at home with a job that I dislike, without much else to do. We're in a very committed relationship, in spite of the short amount of time we've been dating, but I'm still worried that he'll have too much fun to miss me while I have nothing to do but miss him (although I'm going to do my best to try and make fun - I got along without him before!), and I want to do, give, or make something for him so that he won't forget me. It would especially be nice to give him something to take with him and remind him of me. Any suggestions?