I recently designed some Android Apps for the Google Phone. I wasn't sure what to make, exactly, since it seems like there is an application for every conceivable concept ever thunk. These are just a sampling of what I've done, since these are the ones I actually published. I have others that are just experimental, or require hardware that isn't always available.
The first one shown is actually not done yet, the Robot Evolver. It will be a good one, I think. But it is very difficult to design and write for all the variations of device, and to make all the body parts of the evolving robots harmonize correctly.
One I made is something called the "BibleCodeX" A-Z Bible Code Sequencer. It takes the entire King James Bible as a linear row of letters from the beginning of Genesis to the end of Revelation.
It was actually a lot harder than I thought it would be, mostly due to translating my usual C++ kind of thinking into Android's Java language. My other Java coding was less troublesome because it ran on larger Linux machines without the processing limits that a hand held device would have.
Another (for FREE of course) is just the Android Logo with a beating heart. I shouldn't charge for things that are just trademarks belonging to others.
The Deer Hunting Clock is much harder than you'd think. Mainly it is because of the great detail in the clock photo, which causes great memory and time to process in the Android phone. There is another version for 480x854 sized screens, but it consumes so much memory it is unsuitable for sale.
Anyway, I'll keep on trucking, and put some more apps out there, whatever I can think of and have some utilitarian purpose, I guess.