Some good advice on this thread at on Startups for the common situation where an end-user wants a domain that is parked:
Some good quotes:
"Is it a perfect company name or a perfect product name?"
"You need information i.e., what is the Seller willing to sell the domain for? Don't walk away until you know the answer to that question."
"Try e-mailing the contact details in the whois entry. The domain shark has to make money somehow, so maybe you'd succeed. Make sure you pay through an escrow service."
Happy Domain Hunting!