Caution: Mixing services may themselves be operating with anonymity. As such, if the mixing output fails to be delivered or access to funds is denied there is no recourse. Use at your own discretion.
Bitcoin Fog acts as a mixing service or an online wallet. This service operates only through tor anonymization network. Funds transferred to the Fog get mixed with other users' funds. When requested, funds are paid out in multiple randomized transactions to further anonymize the source of money. Comission as of August 4th 2012 is chosen randomly between 1-3% on all deposits.