I'm working on getting two different Rails websites to work together, and ActiveResource is too heavyweight for what I need, so I'm rolling my own interface using YAML and open-uri.
There's a couple good articles about open-uri:
Ruby: Net::Http and open-uri
What's Shiny and New in Ruby 1.8.0?
Data extraction for Web 2.0: Screen scraping in Ruby/Rails
and for YAML: