The Aria Java SDK by Aria provides interaction to the REST and SOAP APIs. Installation and usage show examples to add billing, monetization, and CRM features into Android projects. Aria Developer Central provides instructional documentation, integration tools, and knowledge base with the aim to facilitate implementation.
If you're not familiar with Marco Arment's Instapaper, here's a quick break down. Instapaper is a great little service that allows you to store articles for later on your iPhone or iPad (as of this writing). Instapaper filled a huge gap. Not as high maintenance as an RSS reader, and 100% articles I saw somewhere but didn't have the time to read.