Find a small problem, and build a simple, elegant solution.

FYI, web apps don't make all that much money (convincing users to upgrade to a paid version is surprisingly difficult). Your best bet is to develop a mac or ios app and sell it on the app store.

If you don't know any Obj-C, you could consider developing an app in the language of your choice and running it on Titanium (an awesome IDE from Appcelerator).

I'm also quasi-dropped out of college; I'm the "business side" of a startup; so, as for learning to code, I'm just as much a neophyte as you are.

Good luck, man.