I picked up a couple of those inter-locking eva tiles from Clark Rubber, and did as Barn said, using a 45deg pinpoint router cutter, but went with a diagonal 'diamond-like' pattern. The downside is they are a bit thick, but very comfy!
[edit] Hey Barn, that is an incredibly ugly-looking board! I'm inspired!

I repainted a board a while back after doing some glassing & repairs and was going to give the kids (5 & 7) some paint, walk away & let them go nuts on it, unfortunately there was a good wind the following day and I needed to put a sugarcoat on it, so it's still white.
I'm sick of 'pretty' graphics & symmetrical patterns, going to try to make it into the ugliest board ever!