18. The system of claim 15 , wherein the system is further configured to: retrieve a user relationship map of a user; determine other users that are more than one hop away from the user in the user relationship map; retrieve content by the other users as the extended content; determine quality of the extended content; and combine more extended content than engaging content to the combined list of content if the quality of the extended content is high.
18. The system of claim 15 , wherein the system is further configured to: retrieve a user relationship map of a user; determine other users that are more than one hop away from the user in the user relationship map; retrieve content by the other users as the extended content; determine quality of the extended content; and combine more extended content than engaging content to the combined list of content if the quality of the extended content is high. 21. The system of claim 18 , wherein the system is further configured to: combine approximately a same amount of engaging content and extended content to the combined list of content if the quality of the extended content is not high.