MS took the lead in this category. Back in the 90's I was stuck in their hold queue for some minor issue. Their music was decent, and then a pleasant sounding voice came on, radio DJ style. She told us what song we just heard, and then said something like: "Let's check out the current hold times, shall we? The Office suite hold time is currently estimated at 30 minutes, the SQL Server queue hold time is currently 90 minutes, the Visual Basic hold time is 18 minutes...".
I'm still astounded at the fact they hired someone to sit in a booth and play DJ for hold music.
Inspired me though, at our little regional ISP we set up an old Windows box with Winamp and a cheap soundcard for our music on hold. No repeat workdays for us, heavy on classic rock.