devexpress has them, but they must be purchased.
(they do have a try before you buy as well)
www.devexpress.com
http://www.devexpress.com/Products/NET/Controls/ASP/Gauges/
I have the devexpress controls and I am very happy with what I have been
able to do with them.
In my opinion, you are better off buying the whole asp.net control set
instead of just the guage controls by themselves.
( assuming you can't find them free anywhere ).
They also have a try before you buy, so you can install it on your machine
and give them a test run.
Cheers'
Miro