Are banner exchange sites a good idea? Do you know such?

Most banner exchange programs attempt to link banner ads and sites intelligently, and they often do a good job, but there is a possibility that at some point.

ANY idea may be a good idea :-)
... just ...
"Always listen to experts. They'll tell you what can't be done and why. Then do it!" (Robert A. Heinlein) ;-)
... because - as we know - ...
"The expert knows more and more about less and less until he knows everything about nothing." (Mohandas Karamchand 'Mahatma' Gandhi) ;-P

Most banner exchange programs attempt to link banner ads and sites intelligently, and they often do a good job, but there is a possibility that at some point