When I have domains and websites that I no longer use, I advertise them on Sedo.com.
Sedo.com offers the ability to set the price for selling your domain, you can choose to sell the domain alone, or sell the website of content and domain. They even offer auctions so that you can put your domain up with a minimum bid.
If you have a domain name that you want to park while its waiting to be sold, Sedo.com offers free parking to its customers so that when people visit your page and click on the links, you can make money.
Sedo.com offers all of its services free, but does require a percentage of the total price for which your domain sells. However, if you've got a hot web property, it can sell more on Sedo.com than it might on your own, and you can make money while you're waiting for it to sell.

