The internal combustion engine is SO 19th century. Seriously, it's high time we started looking into other engine technologies and I think that someone has built an electric car that I would drive is great. If we apply the same slowness in innovations to computers, we would still be on PDP-11s.

Here's the thing I don't get; why would you spend time on off hours writing a custom app for your employer when you have down time during your normal work hours? I would talk to your boss about finishing it and deploying it into production and then put it on your resume and move on with your life. Trying to squeeze a couple more pennies out of someone who doesn't seem to have it, to me, seems like a waste of time. The payoff for this will be at your next review or job when you can demonstrate initiative and an increased skillset.