[jarin]

You can host a Sinatra app on Heroku for free. Here's the complete app:

  require 'rubygems'
  require 'sinatra'

  get '/' do
    File.read(File.join('public', 'index.html'))
  end

Just put all of the files in /public and you're good to go.

[pwim]

If you're just going to host static files, just host them directly through Rack as described here: http://mwhuss.com/2009/12/13/static-sites-on-heroku-in-two-l...

Also, make sure you are using http caching - that way Heroku will use Varnish to cache them.