random thoughts for this ;
have some place where users can be sorted by number of shares and “activity” ( number of share/day ).
search by tag, “who are the biggest sharer of “technology” post ?”
search by feed, who are the biggest sharer of “xkcd” post
advanced search by comments, whose post are being the more commented ?
any combination of the above.
based on the tags of my own feeds, searching for the best “match” user.
Thanks for reading.