StumbleUponhas been available on your PC for quite some time (in Internet time) and is available in a mobile edition for Android. StumbleUpon allows you to browse the net for your favorite subjects, so that you can fill your time with unique and interesting content catered to your specific interests.
So I recently acquired a Barnes and Noble Nook e-book reader. For those of you who have not seen this, this is a device which has the e-ink screen which is great for reading books. I was especially interested in the Nook because it runs on Android and operates through touch. The Nook's version of Android is heavily modified so you really cant see the basic Android we are used to on our devices, however there are ways to hack the nook to run your own software on it. (hint search on google for 'nook hack').
The Nook application can be downloaded here on the market.
Wikipathia is a free app in the Android market that gives you two terms or concepts; then it is your job to essentially connect the dots, making the shortest path between the two things using the massive amount of Wikipedia articles as your links. Once you click start, you are given a Wiki list of everything that comes up in common with your starting term. Clicking on a new term will then give you a new list, hopefully leading you closer to the term you are trying to reach. Each time you click on a new term it counts as a path. The goal is to connect the two original concepts with the fewest number of paths.
You can download this application from the market here.
Robo Defense is a very popular game of strategy that involves the purchase and placement of various tower cannons, used to destroy an enemy army. This is a great game of battle that requires you to plan out your purchases with money that is acquired by the successful destruction of your enemy forces. This is an entertaining game of battle.