You can get 3000k Hid kits that would be yellow - another member has done it, might have been on the other forum but i think it was here. let me find it
Ask yourself why you care. If it is strictly for appearance, go with what you like. If you actually want to see in the fog, the best is narrow-band yellow - you can't do this with yellow incandescent bulbs, 300K HIDs are pretty good. Visibility in fog with yellow incandescents is worse than white ones.
i ordered my 3000k HID for fogs last week, its gonna b sick
And Yellow is the most functional color for fogs. for appearance i would match the headlight and Fog colors to give it a better look, but Virginia sucks and has a lot of fog.