gistfile1.rb

#!/usr/bin/env ruby

require 'csv'
require 'net/http'
require 'open-uri'
require 'optparse'
require 'uri'

# You could have used %w[country_code country_name], but I think symbols make
# more sense for such fields.
fields = [:country_code,
          :country_name,
          :region_code,
          :region_name,
          :city_name,
          :latitude,
          :longitude,
          :metro_code,
          :area_code,
          :time_zone,
          :continent_code,
          :postal_code,
          :isp_name,
          :organization_name,
          :domain,
          :as_number,
          :netspeed,
          :user_type,
          :accuracy_radius,
          :country_confidence,
          :city_confidence,
          :region_confidence,
          :postal_confidence,
          :error]

options = {:license => "YOUR_LICENSE_KEY", :ip => "24.24.24.24"}
OptionParser.new { |opts|
  opts.banner = "Usage: omni-geoip-ws.rb [options]"

  opts.on("-l", "--license LICENSE", "MaxMind license key") do |l|
    options[:license] = l
  end

  opts.on("-i", "--ip IPADDRESS", "IP address to look up") do |i|
    options[:ip] = i
  end
}.parse! # end.something looks odd

uri = URI::HTTP.build(:scheme => 'http',
                      :host   => 'geoip.maxmind.com',
                      :path   => '/e',
                      :query  => URI.encode_www_form(:l => options[:license],
                                                     :i => options[:ip]))
# ^ I like aligning, though a parenthesis on its own line looked weird, and
# usually follow the 80-column rule.

response = Net::HTTP.get_response(uri)

unless response.is_a? Net::HTTPSuccess # if not => nuless
  # also parenthesis vs no parenthesis is very arbitrary
  abort "Request failed with status #{respones.code}"
  # ^ abort = $stderr.puts + exit(1)
end

omni = Hash[fields.zip(response.body.encode('utf-8', 'iso-8859-1').parse_csv)]

if omni[:error]
  abort "MaxMind returned an error code for the request: #{omni["error"]}"
else
  puts # puts with no argument does what you want already
  puts "MaxMind Omni data for #{options[:ip]}";
  puts
  omni.each { |key, val| printf " %-20s %s\n", key, val }
   # tons of people have different rules about whitespaces for block
  puts
end