pretty_time.rb

class Fixnum 
  def to_pretty_time
    a = self
    case a
    when 0 then 'just now'
    when 1 then 'a second ago'
    when 2..59 then a.to_s+' seconds ago'
    when 60..119 then 'a minute ago' #120 = 2 minutes
    when 120..3540 then (a/60).to_i.to_s+' minutes ago'
    when 3541..7100 then 'an hour ago' # 3600 = 1 hour
    when 7101..82800 then ((a+99)/3600).to_i.to_s+' hours ago'
    when 82801..172000 then 'a day ago' # 86400 = 1 day
    when 172001..518400 then ((a+800)/(60*60*24)).to_i.to_s+' days ago'
    when 518400..1036800 then 'a week ago'
    else ((a+180000)/(60*60*24*7)).to_i.to_s+' weeks ago'
    end 
  end     
end  

708.to_pretty_time
=> "11 minutes ago"
1708.to_pretty_time
=> "28 minutes ago"
41708.to_pretty_time
=> "11 hours ago"
141708.to_pretty_time
=> "a day ago"
1417038.to_pretty_time
=> "2 weeks ago"