My feed reader is too stupid to understand Sharepoint's stupid NTLM auth scheme, this is a proxy. Its fairly hacky...

app.rb

require 'rubygems'
require 'sinatra'
require 'typhoeus'
require 'base64'

get '/' do
  "hi"
end

# Now you can visit myserver.com/calendar1 and see your feeds!
get '/:feed' do
  username   = "YOUR USERNAME"
  password64 = "YOUR PASSWORD BASE64 ENCODED"
  urls = {
          "calendar1" => "http://example.com/calendar1",
          "steves-calendar" => "http://example.com/calendar4"
         }

  if (urls.has_key?(params[:feed]))
    e = Typhoeus::Easy.new
    e.auth = {
      :username => username,
      :password => Base64.decode64(password64),
      :method => Typhoeus::Easy::AUTH_TYPES[:CURLAUTH_NTLM]
    }
    e.url = urls[params[:feed]]
    e.method = :get
    e.perform
    content_type 'text/xml', :charset => 'utf-8'
    e.response_body
    else
      "Don't know that feed, sorry"
    end
end