Most bank branches have a notary on duty some if not all of the time that they are open. These notaries authorize financial documents for bank employees, but they are also generally available to bank customers. However, there may be some restrictions placed on how they can be used.
Some banks only allow financial documents to be notarized because their insurance does not cover other types of items. It may also be necessary to schedule an appointment to see the notary. Many banks offer notary services for free, but some charge a small fee. It is best to call ahead and find out the rules for a particular bank before bringing a document in.