I have had sales at sedo and although they are not very fast they are good for high value domains and they have different language options so if you are offering your domain to a French, German or Spanish buyer you can redirect them to the sale page on their language.
For low value domains I'm experimenting with namecheap for a while. Their marketplace is very interesting. You can only list the names for sale in your namecheap account but you can do so within your control panel. It is very convenient. Also everthing works very smoth and instant unlike moniker's website. One big adventage on namecheap marketplace is that when the domain is sold it is gone from your account. No further action is taken. The moment the buyers pays the name is gone to buyers namecheap account and the money is in your namecheap accout. Of course they hold the money for 10 days and the domain for a while in their system but the buyer can start using it immediately and you see the amounth waiting in your account. You can also forward the url to your own sale page. Example: neurogenesis.net
Some time ago since I didn't know about moniker's marketplace I decided to try it out myself. I've put one of my domains registered at moniker to moniker marketplace. Then I created a new moniker account and went to the sale page and bought my own domain. So far it has been 21 days and I have emailed them 4 times and I'm still waiting. Neither the money is in my first account nor the domain is in my second account. The domain is also not in my first account since it is transfered to a escrow account.
I have emailed them telling that they didn't need to do this for moniker domains. If the seller is selling a moniker domain and the buyer is buying with a moniker account what is the point keeping both sides for weeks? They should just make sure the domain doesn't leave moniker. Their terms mention 60 days. I'm pissed off with moniker.