snostorm (dpreview panasonic forum, 29 January 2004) describes how LED keychain lights can be used as a focus-assist light. slipe (dpreview, Minolta forum, 21 February 2004) uses a Photon III attached to a watchband (and another post on Panasonic forum).
Other people use a laser pointer, preferably with a `pattern', rather than a dot, projection. Some external flashes will also project a focus-assist light.