mongoid_will_pagnate is a gem for native support of will_paginate for mongoid. It allows you to do lazy load of your collections with pagination using native calls to Mongoid::Collection#skip and Mongoid::Collection#limit.
Just add this gem to your Gemfile:
gem 'mongoid_will_paginate'
and you can use will_paginate without fetching all collection objects to array (like it does internally) while paginating.