1. A method for generating signals from distributed data source computers controlled by a multiplicity of owners for selling in a signal marketplace, the method steps comprising: a data processor at a first data source computer generating at least one first signal having at least one first signal payload from first raw data stored on the first data source computer, wherein the first raw data includes structured data and unstructured data, wherein the unstructured data and the structured data include records associated with a behavior and/or an event associated with a first object; the data processor at the first data source computer correlating the first object within the first data source computer with a first unique hashed value, wherein personally identifiable information of the first object, including an email address of the first object and a credit card number of the first object, is not revealed by the first unique hashed value; a data processor at a second data source computer generating at least one second signal having at least one second signal payload from second raw data stored on the second data source computer, wherein the second raw data includes second structured data and second unstructured data, wherein the second structured data and the second unstructured data include additional records associated with a behavior and/or an event associated with a second object; the data processor at the second data source computer correlating the second object within the second data source computer with a second unique hashed value, wherein personally identifiable information of the second object, including an email address of the second object and a credit card number of the second object, is not revealed by the second unique hashed value; the first data source computer providing the at least one first signal and the first unique hashed value to a centralized database associated with a virtual marketplace server computer; the second data source computer providing the at least one second signal and the second unique hashed value to the centralized database associated with the virtual marketplace server computer; the virtual marketplace server computer indexing the at least one first signal and the at least one second signal in a signal index in the centralized database based on signal ownership, historical usage, historical performance, and relevance to an objective; wherein the at least one first signal payload and the at least one second signal payload each include an identification of a source, a delivery channel, and a transaction identifier; wherein the at least one first signal and the at least one second signal originate from different distributed data sources controlled by different owners; the virtual marketplace server computer automatically determining and assigning a value to the at least one first signal and a value to the at least one second signal in the centralized database based on a recency of each signal, a time of construction of each signal from an occurrence of a desired event and/or a desired behavior, a reputation of each signal, historical performance of each signal, and a reputation of each seller associated with each data source computer, and wherein the value of each signal is associated with its corresponding indexed signal in the centralized database; the virtual marketplace server computer receiving from a signal buyer computer a reference point including the desired behavior and/or the desired event and parameters for the desired behavior and/or the desired event, the parameters including a recency or a frequency of the desired behavior and/or the desired event; the virtual marketplace server computer constructing at least one synthetic signal from the at least one first signal and the at least one second signal based on the desired behavior and/or the desired event and the parameters for the desired behavior and/or the desired event; the virtual marketplace server computer automatically recommending the at least one synthetic signal and a price for the at least one synthetic signal to the signal buyer computer based on the value for the at least one first signal, the value for the at least one second signal, the relevance to the desired behavior and/or the desired event, and the parameters for the desired behavior and/or the desired event; the virtual marketplace server computer sending the at least one synthetic signal to the signal buyer computer upon receiving an acceptance of an agreement related to use of the at least one synthetic signal from the signal buyer computer, the agreement including a defined use for the at least one synthetic signal by the signal buyer computer; the virtual marketplace server computer automatically tracking feedback relating to the at least one synthetic signal including signal performance using the first unique hashed value to identify the first object and the second unique hashed value to identify the second object, the feedback including events, behaviors, and/or states of the first object and/or the second object subsequent to the defined use for the at least one synthetic signal by the signal buyer computer; the virtual marketplace server computer automatically updating the signal index, the value of the at least one first signal, and the value of the at least one second signal based on the feedback, including updating the historical performance of the at least one first signal and the historical performance of the at least one second signal based on the signal performance of the at least one synthetic signal; wherein the at least one first signal and the at least one second signal have a common signal structure, thereby creating a common taxonomy to enable exchange of the at least one first signal and the at least one second signal in the signal marketplace; wherein the at least one first signal and the at least one second signal do not disclose the raw data from which each signal is created, and wherein the raw data remains localized on the first data source computer or the second data source computer; and wherein the value of each signal decays over time.