Scrapbook!! or really anything that is handmade. Find some way to put together mementos from your wedding or some other special time you had together. A pocket scrapbook he can keep with him or a hand decorated picture frame he can put on his desk at work.

Make him commit to spending a certain evening/afternoon/day with you to celebrate--no backing out. And then just buy him tickets to something during that time (a sporting event, play, etc). That way he can't have bought them for himself because he's committed the time to you.