Over the last many months I have been reading about this technology and eagerly looking to find a service that would help us easily use and manage such an account. Below are all of the easy to use options that I know of and have experimented with. If you don't have a clue what multi signature transactions are, start here, but the basic idea is having to use more than one private key to sign a transaction to spend funds from a given account. This type of account can be shared by multiple users but also allows for one person to have to sign and manage 2 of 3 keys adding a security layer for individual users and not necessarily having to have multiple people sign off on a transactions.

BitGo was the first to bring a multisig product to market and in March of this year started offering enterprise grade accounts to business and bitcoin enthusiasts. BitGo does make their wallet free for the general public but the tools and feature sets are targeted at businesses with a need to secure large bitcoin holdings. Implementing a wallet like this is easy but a number of steps must be taken to set up the account properly. The wallet should require your company to have a technical/security officer who would implement the account and secure the relevant data and master keys. This person would have no signing authority but would play a critical role in keeping this information backed up and safe. In addition, some amount of training would likely be needed for the staff that does have signing authority: your accountants, office managers, and CFO. If this sounds like your use case, this is the best and most widely used professional account on the market. In the end, I did not find this to be the best tool for our small organization but I have retained a security officer who will help us implement this wallet in the coming year.

Coinbase announced its Vault service earlier this year and on Oct 29th announced that this system was now operating with multi signature technology under the hood. The blog post also noted a new feature of this wallet to allow users to control their own private keys; specifically the ones used in a multisig agreement.