Why Is My Web Service API Crappy? twitch.nervestaple.com
Christopher Miles has a great article: Why Is My Web Service API Crappy? and it's definitely worth a read if you're building externally facing APIs.
extend with objects and modules.gem install radiant --pre and try out the RC2.
gem install radiant --prethe_site.com/admin/disable/your_secret_key. Once your customer has paid her bills, just post to the_site.com/admin/enable/your_secret_key