Experiment on making a browser/android-based MMO using GWT to offload a lot of heavy processing to the client (and save on those pricey cloud cpu charges)
http://www.gloopsh.com/
General idea is that each player controls a bunch of soldiers that they can equip and give battle tactics to (flank, use abilities, etc). Battles get auto-resolved with a nice graphical replay (you can check out an early version of that by clicking the bottom right button on the page), so anybody can attack anybody else on the map regardless of whether they're 'online' or not.
Currently coding up a stock exchange based economy for the game so that there are caravans moving between cities for players to raid and generally make the world seem a bit 'alive'.
Obviously a pretty big project to be doing with one guy and part time, but it's surprisingly coming along pretty nicely!