Psytechnics, a company that was spun out of British Telecom, has a cool product called Experience Manager. The product is one of the few I know of that can measure both QoS (quality of service) and QoE (quality of experience) for voice and video applications on the IP network. Many network management vendors are good at detecting jitter, packet loss, etc., for voice and video, but Psytechnics is able to measure how the end user is experiencing these services on an endpoint device.
Here is Tom Casey, a sales engineer with Psychtehnics, demonstrating the operational interface of Experience Manager, recorded last week at VoiceCon Orlando. Sorry for the jittery camera. I drank too much coffee.