If you're working with web APIs in Android apps (and want to do it in the most efficient manner), you may be interested in this talk on Consuming Web APIs in Android Applications:
There's also a blog post Bill Donahue at MeetMe's engineering blog to go along with it.
Do you already have an Android application or are looking to create a new one that consumes web APIs, then this is the talk for you! This presentation will cover modern best practices on how to consume web APIs using the latest open source libraries. Learn how you can download and parse web APIs with a minimal amount of work, while also getting the benefits of a HTTP cache, gzip support, connection pooling, and SPDY support.
You will learn how to start with an application with no API usage and make use of an OkHttp, GSON, and Retrofit stack. Using this stack, as well as code generators, you will learn how you can parse most web APIs in about five minutes.