1. A computer system configured to select a transaction for a certain user based on similarity of a profile of the certain user to profiles of users belonging to different organizations, comprising: at least one processor and memory; the at least one processor and the memory cooperating to function as: a transaction identifier configured to receive activity data obtained by monitoring activity of the users on software systems belonging to the different organizations, and to identify transactions executed by the users on the software systems; a profile generator configured to generate profiles of the users based on the transactions; wherein a profile of a user indicates transactions executed by the user; and a transaction recommender configured to receive a profile of the certain user; wherein the certain user belongs to a certain organization that is not one of the different organizations; and wherein the profile of the certain user indicates transactions executed by the certain user on a software system belonging to the certain organization; the transaction recommender is further configured to select, based on similarity of at least some of the profiles of the users to the profile of the certain user, a certain transaction; wherein the certain transaction was executed by a user with a similar profile to the profile of the certain user; wherein first and second profiles that are similar are characterized by at least one of: number of transactions described in the first profile that are also described in the second profile reaches a first predetermined threshold greater than one, proportion of transactions described in the first profile that are also described in the second profile reaches a second predetermined threshold, and a value of a similarity function that receives representation of the first and second profiles as input reaches a third predetermined threshold.