I know for Sedo which is free. Flippa need payment if I'm not wrong. There is new player, FreeMarket.com (Freelancer devision) but not many buyers at the moment. Any other?
FreeMarket is still pretty new, but they have the money to grow pretty quickly. You could also look over the following: -GoDaddy Auctions -Afternic (Also owned by GoDaddy) -Bido -DNX -CAX -4.cn
You can sell it on Flippa... You get a free listing after you appraise 15 domains... It only takes a few minutes to appraise them... Just type random numbers. Just go under the domains tab and click appraisals and start appraising 15 domains...
Above.com has a domain marketplace where you can list your domains for free for as long as you want. You just pay 10% once it sells. Free escrow.