Market value for Domains with type-in traffic.

Just wondering, has anyone got an idea about those "Premium Domains" that enjoy traffic comes from direct type-ins, what's the market share that it grabs from the overall paid search business? Eg, when people just type in cellphone.com when they wanted to look for cellphone related information. So, if cellphone.com is a landing page with PPC link all over it, I am sure the visitor will "click" on the link and the domain owner get paid for the PPC.
(this example is just for illustration only)

My rough estimation for it is like "should be" well over billions . Anyone got further information? Well, it for sharing and to get ourselves "motivated" while we continue to "hunt" for good domain names

That's interesting as a concept. I don't do that so it was especially noteworthy that people even do it. I google and while I've come to suspect the paid and premium companies which come up as too commercial (and usually the most expensive too), I hadn't thought of using the possible domain name as a search vehicle.