Processing JSON data from an external source with Javascript templates is a natural fit. Create a template inside your HTML Document by adding class names and variables and write a few lines for fetching the JSON, that’s all. This tutorial is an example for my Javascript Template Engine called Patroon.
You need a del.icio.us sidebar which shows recent bookmarks or one of these nice flickr badges? This is really is easy as the Typo Weblog Engine already includes an flickr and del.icio.us aggregator.