In There Will Be Blood (2007), there is a scene where Paul Sunday sells information about there being oil where he grew up.
This struck me as something very difficult to negotiate, because, while this information is very valuable, it's not a patent. Until the buyer investigates it, he does not know how valuable it is. But after the buyer knows the details, he has no incentive to pay for it.
If you were in Paul Sunday's shoes, and wanted a lawyer to represent you in the negotiation, which legal specialty would you go with?