I think you meant "Rack" and not "Rake". If so, here is a method to add a parameter to the query string :

use Rack::Config do |env|
  env["QUERY_STRING"] += "&" unless env["QUERY_STRING"].empty?
  env["QUERY_STRING"] += "" + Rack::Utils.build_query(:my_new_parameter => "and its value")
end

2011/4/24 Lee Hambley <lee.hambley@gmail.com>
Example please Ned… (the code you have so far)