LEDs do not have the light output characteristics yet to be competitive with halogens or hids yet. You would need to use multiple really high power LEDs like luxeon stars (
http://www.luxeon.com/products/family.cfm?familyId=2) fitted into a custom array to even achieve the potential for use as fog lamps. Those bulbs you linked aren't gonna light up crap. At best, as those latter two auctions clearly state, you might be able to use them as DRL's or city lights, and even then I wouldn't bother over a conventional halogen bulb which is cheaper and brighter. Plus you've gotta be insane to pay $100 for those PIAA's since they're going to be auxilary lights that don't even match up to halogens.