I am extremely proud of what we have built at Picplum. This presentation has a good overview of the Picplum.com and Picplum Prints API internals.
Picplum.com is a Single-page backbone app that is built on a set of restful APIs. There are plenty of tricks and trips around building APIs', backbone.js and single-page apps.
This presentation was created for O'Reilly 2012 Fluent Conference http://fluentconf.com/fluent2012/public/schedule/detail/25389
Oh and hey, send some free prints on us :)