I don't know what the highest bungee jump in the world currently is but here is the potential for a 4,000 foot bungee jump if they will let you do it and if anybody is up for it. What sort of speed do you think you'll be travelling at when that elastic band pulls your hips out of their sockets?
The Grand Canyon Skywalk opens on the 28 March 2007. This glass bottomed horseshoe shaped skywalk will extend 70 feet out into the canyon and hover 4,000 feet above it. Don't think that it's fragile though. It has been built to support the weight of 71 Boeing 747's, gale force winds and 8.0 magnitude earthquakes.
View arial image from Google Maps (zoom 1 level out after opening image)