I use the DX flashlight clamp (it's a popular item, many have it!) either mounted on an original gorillapod (magnetic) or mounted to a very strong table clamp.
The suggested DX swivel tripod for flashlight is a good unified solution, very nice! Not as flexible and versatile as a gorillapod but optimal for those who need exactly this and not a more flexible holder solution (like the gorillapod or table clamp).