I put LED conversion bulbs in my OEM taillights, and I am happy with the result.
http://www.superbrightleds.com/cgi-b...5-T.htm#photos
I also used some of their other bulbs in my father's Pontiac G6 center brake light, and he is happy with the result. I had to use an adapter that allowed the use of a 194 series bulb in a twist lock bulb socket. Those adapters were sold at CarQuest.
When I had my Saturn ION, I used some "Jamstrait" LED bulbs that used to be sold at AutoZone to convert my center brake light, and the results were excellent.