How about painting it with some high gloss enamel house paint in your favorite colors and designs and mounting some legs on it and using it as outdoor furniture for a patio or deck, an outdoor coffee table. I love the idea of an outdoor room and I had one once but we moved and haven't had one since. Of course I've never seen a surfboard in person maybe they are not shaped in such a way that they would make a good table. You could use it as a canvass and paint it and hang it on your wall, of course you would need large wall space. If you have kids or grandkids you could get them to paint it and hang it up as an art piece (I love kid art, it's so cool, almost worth having kids for). Good luck and once you figure it out post a photo so we can see what you did with it.