I operate a highly profitable web site where a member suggested a new feature that is a play on the name of the web site. We've added the feature, and it has become pretty popular.
We've been looking to change the domain name of the site because the current name is too long and doesn't really reflect the type of site that it is. We've located a reasonably priced domain name that would work. It is the name of the feature mentioned above, and since it is a play on the current domain name it would provide a smooth transition to the new name.
My question is, would we be opening ourselves up to some sort of responsibility to pay the member who suggested the name and the feature in the first place? I guess I'd be willing to pay him a few hundred dollars to get him to sign something saying he gives us full rights, but he could potentially want a lot more than that and offering him money could make him think we owe him something.