I had a pair of MTEC Xenon 501 sidelight bulbs lying around spare so I stuck them in the rear number plate.
Colour is much whiter than the standard yellow/beige from normal bulbs, especially suits my car being white!
Sorry the pic isn't clear, my camera isn't the best!

and here is the link to the bulbs in question:
http://www.ebay.co.uk/itm/MTEC-SUPER-WH ... 3f0c0b3f72