There are many companies who use Usability Sciences services. One of them is called Attitudinal Analytics for conversion improvement. It analyzes key performance metrics, demographic breakdown, funnel analysis,etc. There main business is in the usability area. With more then 20 years of experience and a long lists of clients, like: Aetna, American Funds, American Heart Association, Autodesk, Bank of America, Dell Inc., General Electric and many others, it seems that this is the most popular and favorite usability testing company in the world. Has anybody heard about them?
Large companies chose them to elevate user experience in their website and gain advantage over their competitors. Anyways, worth a look.