I have one of these gizmos. It works surprisingly well and isn't too ugly. Weighs next to nothing and not too expensive.

http://aebike.com/product/elite-vip-...c9155-qc30.htm

You have to have a pretty straight fork leg tubing section about 80mm long for this gizmo to work. Most all forks, even traditional curved forks, have an adequate straight run near the top of legs.

You may want to use some scrap inner tube rubber between fork leg and gizmo to protect finish and provide extra no-slip friction. Cloth tape (or duct tape) works too.