This gem generates a URL slug/permalink based on fields in a Mongoid model.
class Book include Mongoid::Document include Mongoid::Slug field :title slug :title end >> book = Book.create(:title => "A Thousand Plateaus") >> book.to_param "a-thousand-plateaus" >> book.update_attributes(:title => "Anti Oedipus") >> book.to_param "anti-oedipus" >> Book.find_by_slug("anti-oedipus") #<Book _id: 4c23b1f7faa4a7479a000009, slug: "anti-oedipus", title: "Anti Oedipus">