I think it's pretty nice. Get all records within a railsified period of time (7.days.ago, 12.months.ago). I can do cool things like Workout.within_12_days or Workout.within_12_hours. Further conditions can be given as a hash, and will be transposed onto the end of the :conditions.

Workout.within_n_units(:user_id => 12) #-> Workout.find(:all, :conditions => 'created_at > n.units.ago and user_id = 12')

class Workout < ActiveRecord::Base
  class << self
    def within_n_temporal_units(number, units, further_conds={})
      conds = "created_at > '#{eval("#{number}.#{units}.ago").to_s(:db)}'"
      further_conds.each {|key, val| conds << " and #{key} = #{val}"}
      Workout.find(:all, :conditions => conds)
    end
    
    def method_missing(name, *args)
      return within_n_temporal_units($~[1], $~[2], args[0] || {}) if name.to_s =~ /within_(\d+)_(\w+)/
      raise NoMethodError, "undefined method `#{name}' for #{self}:Class"
    end
  end
end