This thread is certainly worth a bump, and I can reiterate what John has suggested about IT and Web companies being good middlemen.
This past Saturday a marketing agency sent me an email through the parked page of one of my domains at NameDrive asking if I want to sell and for how much.
I quoted him a price of $900, saying this is a good deal because I will not normally sell this domain to any end-user in the xyz industry for under four figures (my domain is like XyzGeo.com)
In my reply i included all my company contact info including phone number in the signature. Sure enough I got phoned up yesterday by this company in response to my quote. He called to ask some questions about traffic, etc. Then he asked if I can also provide the web-design and development, and if I can put together another quote for that. So what he want's is the domain + turnkey lead gen. solution for his client. He will buy from me the domain + website package, so he can upsell to his client with additional marketing/ppc services.