Here is a ruby script to get Alexa traffic rank for specified site.

    1 #!/usr/bin/env ruby -w
    2 
    3 if ARGV.empty?
    4   puts <<-T
    5 alexa rank checker by dairon
    6 usage: alexa <url>
    7   T
    8   exit
    9 end
   10 
   11 require 'open-uri'
   12 
   13 url = ARGV[0]
   14 rank = "-1" # no data
   15 open( "http://alexa.com/data/details/traffic_details?url=#{url}", "r" ) do |f|
   16   fstr = f.read
   17   fstr.squeeze!(" ")
   18   fstr =~ /Traffic Rank for(?:.+?)-->(.+?)<\/span>/
   19   break if $1.nil?
   20   rank = $1.gsub(/<(.+?)>/, "").gsub(",","")
   21 end
   22 
   23 puts rank