John Todd wrote:
When I'm on hold with a vendor and I get music (or worse, ads) pumped
into my ear, I will often ask for the manager on the next opportunity
that someone comes on the line.
I'm exactly the opposite. I don't necessarily want to hear ads, but I
don't like not quite being sure whether I'm connected or not 
Back when I worked in the CAIS NOC, many years and at least
one buy-out ago, we wanted to build a music-on-hold system
that played really dark, eerie ambient music -- Coil is a
good example, for those who know it. Of course, we really
wanted to be BOFHs back then.
Now, I'd probably choose Brian Eno's "Music for Airports"
and similar calming, inoffensive tracks. But again, no ads
of any type -- if you're calling because your service is
broken, nothing will increase your anger faster than some
smarmy salesperson talking about 100% uptime.