AVScience, the sponsors here makes them. Digital Connection, whose employees hang around here a lot and contribute make some good stuff too. Cellar Cinemas also looks pretty cool, but I have no experience with them.
Are you looking for a person to make one, not a company? One of the moderatos here, xcel, has done them on occassion I believe...
Most of these companies are quite small affairs. I imagine you get a real person you can talk to at all of them. AVS subcontracts their HTPCs out to one guy who you can talk to on the phone all the time I think.
What exactly are you looking for that you only want to get it from a person?
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