Bad idea to write to them imho. Any profiting you attempt to do from the site will most likely not please them. If you ask them and they then tell you that you can't profit or else...well basically your domain is junk. But here goes anyways: Dear American Airlines, I am the owner of the domain american-airlines.info. I am contacting you to ask permission to use this site for a fan information site. I plan to have some Google Adsense ads to help me pay for hosting and domain renewal expenses. If possible I would like to be able to use your logo on the site only to represent that american-airlines.info is a fan site of your service. I can surely place a notice on each page of the site declaring we are unofficial and not endorsed nor associated with your company. I can also place a direct link to your official site. I thank you for any consideration you can give me. Please feel free to contact me any time. If I do not here a reply within 15 days of this email I am going to presume you have no problems with my ideas and will proceed. Thank you, Mr. X 555-555-5555
Well some say do it and see what happens, some say contact and see how they feel, and some say sell the domain and forget about it. Thanks for writing that up. Much much better than what I would have came up with How does one even know how much a domain is worth?