What is the best way do sell or market domain names I own ?

I own several domain names and I know alot of people park their domain and try to collect ad revenue off of it. There are a couple of domains I own that I know are worth alot because of the rights to the books and a movie company buying the rights to the film series has taken place. Tunnels is a book series that is due out in January 2008 in the US and already released in the UK. It is being billed as the next Harry Potter, I own the domains tunnelsbook.com and tunnelsmovie.com. How can I market them to sell them to someone who wants to develop them to cash in?