acts-as-taggable-on and friendly_id together

Need slug for tags?
Put code below into config/initializers

ActsAsTaggableOn::Tag.class_eval do
    extend FriendlyId
    friendly_id :name, :use => :slugged
end

and don't forget add slug column to tags table

you can find it here https://github.com/maciekkossuda/initializers