You want Arduino-to-the-max? With a great variety of add-ons? This is the official made-by-Arduino super-development kit, all plug-and-play! Can-we-add-more-hyphens? Let's try!
So you want to get into the Arduino development system, but not so enthused by all the soldering? Good news - the Arduino team has released the ADK TinkerKit.
The ADK TinkerKit is a complete pack of 25 TinkerKit Modules (listed below), Arduino Mega ADK, Mega Sensor Shield, and necessary wires to kickstart your Android development experience without soldering. In short - you get an Arduino Mega with sensor shield and all the plugs to connect them to 25 little interface modules!
TinkerKit modules simplify electronic prototyping by allowing the user to rapidly hook up new sensors and actuators using 3-pin cables. This handy development kit expedites prototyping allowing the user to concentrate on the project instead of wasting time soldering.
The Arduino ADK Mega board itself is an upgrade to the standard Mega in that is has a USB host controller - this is Google ADK compatible! You'll be able to connect this to your android device!
Specifics regarding the modules are available here.
Want to dive into Android development? Here's where to start.