you can buy wedge LED lights that fit in the sockets just the same as the halogen bulbs, they're size 74 and 194 i believe, and you can get them from various websites or ebay. i changed mine to red not too long ago, and it looked great, but for some reason, after the first 3 or so times, everytime it turned out it just blew the fuse, very frustrating, but i've never heard of this happening to anyone but me.
also you can buy overlays, which are a bit trickier to install but look great, and ive heard of bulb paint as well