flickramazondel.icio.usとupcomingの個人情報を一ヵ所にまとめたAdactio elsewhereで共通するのはすべてのサービスがapiを公開していること。データのやりとりにはsoapxml-rpcでなくrestを使っており,ajaxを使っているのでページまるごとの再読み込みがない。最初にjavascriptを使わなくても機能するサイトを構築してから,ajaxを適用させたレイヤーをかぶせるprogressive enhancementの考え方で作られたこのサイトのビルド過程をドキュメント化したものがいずれ公開されるとのこと。

All of those sites I mentioned have something in common. They all provide APIs. I like the idea of using each API to display the different services in a combined way.
I'm using RESTful requests to send and receive information from each web service. This isn't out of any ideological bias against SOAP or XML-RPC, it's just the simplest and easiest way to get something up and running.

To me, it makes sense to first build your application using old-fashioned server-side technology to do all the work with old-fashioned page refreshes to display updated information. Once you've got that built, you can then apply JavaScript to make a better, richer, more usable application. By intercepting the default actions with JavaScript and replacing them with XMLHttpRequest calls, you can add a lovely layer of instant interaction. But, and this is the kicker, you know that your smooth, slick application will degrade gracefully in browsers that don't support JavaScript.
It's called progressive enhancement and it's how we should all be building our web applications. The concept forms the basis of applying CSS correctly. Ideally, we should be following through on this idea whenever we decide to wield the scalpel of JavaScript.