Visit my buddies at
Susquehanna Motorsports Home Page and get some Optilux Extreme Yellow bulbs. I had them in my stock fog lamps (changing them out for Hella's, more on that later) and they are very yellow and very bright. Quite effective when it's actually foggy and not to shabby looking the rest of the time.
Here's a link to their H11 page:
Hella H11 Replacement and Upgrade Bulbs