The best place is to sell from your own site with the domains are parked on it. If you aren't up to that or don't have very many, then in addition to the above I'll add fabulous.com. If they are one word domains, greatdomains.com may accept them. If you are confident in value, pool.com marketplace makes some sales (but listing prices are steep). If registered at registerfly.com, their marketplace has also sold a few for me in the past (I heard they may start listing names not registered there). There are a couple other (unnamed) forums as well.
One of the worst places most newbies start is ebay. Expensive, low sales success, and too short a listing time.
Good luck.