Head on over to DevX to read a Special Report feature on SaaS and Building On-Demand Applications in the Cloud. This report consists of five articles around building applications for On-Demand including Force.com, Amazon and Bungee Labs.
I’d like to especially thank E.J. Wilburn of CRMFusion for contributing a great article and tutorial for this Report. You can read his article Getting SaaS-y with Apex and VisualForce.