I shoot concerts. I have a couple of very tall tripods, but they are too heavy to carry around in my kit. But the ones I carry are limited in height. And, inevitably, any person over 6' will position him or her self between my cameras and what I'm shooting. (Last week, there was a couple, and BOTH of them were over 6' 2")

Does anyone make a tripod that I could mount a Manfrotto 501 head on that can use to raise my camera over 6' that weighs less than 8 lbs? Does anyone make a tripod with telescoping legs with four segments instead of three?

Don't know for sure, but have you considered getting a lighting stand and modifying the top? That should bet you to about 8 feet and most are very light weight.

The Manfrotto 3258 / 161MK2B will take your 501, and extend to almost 9' high, but it weighs 17.5 lbs.

Extremely solid.

I understand why you want 8 lbs., though. This thing is a beast.

I asked a similar question a month or so ago.

Also see this thread...

http://www.dvinfo.net/forum/tripod-sticks-heads/515285-tall-sticks.html

You should have a look to the Manfrotto 536 with a 520Ballsh. Tall, light and four segments legs!

You should have a look to the Manfrotto 536 with a 520Ballsh. Tall, light and four segments legs!
That tripod looks very good for above-average height and light weight. The 3258/161 will go significantly higher, but that extra height is only usable if you are standing on a stepladder or some other platform to operate the cam.