Display comment count in a view
This small Views user: comments relationship patch should be just the ticket: http://drupal.org/node/1773966


  ...I ended up creating a "User: Comments authored" relationship. Very
  useful. Combined with aggregation and using "count distinct" it allows
  a user view to include # comments authored and # of nodes authored.


Direct link to patch: http://drupal.org/files/views-uid_comment_relationship.patch