I've pulled together a Rack adapter for Couch's external protocol, which allows you to run a Sinatra app as an external.
More details in the Readme: http://github.com/gbuesing/couchdb-rack I built this so that I could mount some legacy Ruby code as small services to be consumed browser-side by an Evently Couchapp. This approach saves me from having to set up another web server to host the Ruby code. Also, I have access to the userCtx within Sinatra if I need it. Interested in feedback on this approach, and/or if others would find this code useful.
