A newcomer on the block is Bido who auctions domain names. However they only auction 1 per day, therefore at most 365 per year will be auctioned through Bido.
If you are looking to have your domain auctioned by Bido they take an 8% commission rate. Each bid starts at $1 and they guarantee a minimum price for the seller. They allow individuals to make comments regarding the domain to be auctioned, Bido calls them experts.
Due to the low volume of auctions they also provide domain name portfolio management.
Take a look at Bido.