Since most activity logging solutions out there are either complex or require controller hacking i based this new dead-simple activity logging plugin on userstamps.

Thats 16LOC for complete activity logging…

Record Activities Rails plugin

class Comment < ActiveRecord::Base
  stampable
  record_activities #same as record_activities  :create, :update
end
Comment.create! -> Activity(:subject=>comment,:actor=>current_user,:action=>'create')