1. A computer implemented method, comprising: identifying, by a data exchange engine executing on one or more processors, one or more user lists based on owned or permissioned data, each user list including a unique identifier; associating metadata with each user list including data describing a category for the user list, population data including recency of updates of members of the user list or subscriber reviews of the user list, and subscription data that includes subscriber cost information for subscribing to the user list including a cost for using the user list as selection criteria for a campaign and restrictions on combining user list data with other data including restrictions on using the user list data with data associated with a particular geographic region or data associated with a particular category; storing in a searchable database a user list identifier and the associated metadata for each list; publishing for potential subscribers a list of the user lists by providing an interface that includes for each user list the unique identifier and the associated metadata; after the publishing, receiving one or more criteria from a potential subscriber to a user list wherein the criteria includes a category, recency threshold, review threshold, cost threshold or restriction threshold; evaluating the received one or more criteria to determine one or more candidate user lists that satisfy the one or more criteria for presentation to the potential subscriber; and presenting candidate user lists as a recommendation to the potential subscriber.
1. A computer implemented method, comprising: identifying, by a data exchange engine executing on one or more processors, one or more user lists based on owned or permissioned data, each user list including a unique identifier; associating metadata with each user list including data describing a category for the user list, population data including recency of updates of members of the user list or subscriber reviews of the user list, and subscription data that includes subscriber cost information for subscribing to the user list including a cost for using the user list as selection criteria for a campaign and restrictions on combining user list data with other data including restrictions on using the user list data with data associated with a particular geographic region or data associated with a particular category; storing in a searchable database a user list identifier and the associated metadata for each list; publishing for potential subscribers a list of the user lists by providing an interface that includes for each user list the unique identifier and the associated metadata; after the publishing, receiving one or more criteria from a potential subscriber to a user list wherein the criteria includes a category, recency threshold, review threshold, cost threshold or restriction threshold; evaluating the received one or more criteria to determine one or more candidate user lists that satisfy the one or more criteria for presentation to the potential subscriber; and presenting candidate user lists as a recommendation to the potential subscriber. 26. The method of claim 1 , wherein the recommendation is based at least in part on concepts provided as part of an advertising campaign planning operation.