This post includes an improved version of the query example in Ruby for hitting the Alexa Web Search web service. Sample usage is as follows.

require 'alexa'
Alexa.search('bogle').each {|hit| puts hit.title}

For convenience, you might want to edit the code below to replace INSERT_YOUR_ACCESS_KEY_HERE with your actual access key and INSERT_YOUR_SECRET_ACCESS_KEY with your secret access key; otherwise these will need to be passed in as the AWSAccessKeyId and SecretAccessKey options.

alexa.rb

#/usr/bin/ruby

require "cgi"
require "base64"
require "openssl"
require "digest/sha1"
require "uri"
require "net/https"
require "rexml/document"
require "time"
require "ostruct"

module Alexa

	# search for "query", returning "count" rows starting at "start"
	# Note that the maximum count is twenty.
	def search(query, start = 0, count = 20, options = {})
		options["Query"] = query
		action = options["Action"] ||= "WebSearch"
		options["AWSAccessKeyId"]  ||= "INSERT_YOUR_ACCESS_KEY_HERE"
		options["Start"] = start
		options["Count"] = count
		options["Timeout"] ||= 9000
		options["ResponseGroup"] ||= "Results"
		secret_access_key = options["SecretAccessKey"] || "INSERT_YOUR_SECRET_ACCESS_KEY"
		timestamp =  options["Timestamp"]  = Time.now.utc.strftime("%Y-%m-%dT%H:%M:%S.000Z")
		options["Signature"] = compute_signature(action, timestamp, secret_access_key)

		url = URI.parse("http://websearch.amazonaws.com?" + query_string(options)) 

		xml = REXML::Document.new( Net::HTTP.get(url) )
		doc = xml.root

		results = AlexaResultSet.new

		begin
			results.total_count = REXML::XPath.first(doc, "//aws:TotalCount").text.to_i
		rescue Exception => e
			results.total_count = 0
		end

		timeout_node = REXML::XPath.first(doc, "//aws:TimedOut")
		results.timed_out = timeout_node and timeout_node.text=="true"

		for element in REXML::XPath.match(doc, "//aws:Result")
			results << (result = AlexaResult.new)
			for field in REXML::XPath.match(element, "aws:Field")
				result[field.attributes['name']] = field.text
			end
		end

		return results
	end

	class AlexaResultSet < Array
		attr_accessor :total_count, :timed_out
	end

	class AlexaResult < Hash
		# define a method called method_name to fetch field_name
		def AlexaResult.field_accessor(method_name, field_name)
			class_eval "def #{method_name.to_s}; self['#{field_name}']; end"
		end

		field_accessor :url, "DataUrl"
		field_accessor :title, "Title"
		field_accessor :size, "CrawlDataSize"
		field_accessor :score, "Score"
	end

	def compute_signature(action, timestamp, secret_access_key)
		digest = OpenSSL::HMAC.digest(OpenSSL::Digest::Digest.new( "sha1" ),
									  secret_access_key, action + timestamp)
		Base64.encode64(digest).strip
	end

	def query_string(options)
		options.to_a.collect {|item|
			item.first.to_s + "=" + CGI::escape(item.last.to_s) }.join("&")
	end

	module_function :search, :compute_signature, :query_string

end