[eli_gottlieb]

>I've though about leaving my program because I'm so dispassionate about the work. I really just want to build something cool, interesting and useful.

Suck it up. "Cool, interesting, and useful" comes after you've made enough money to pursue passion projects, if you get lucky in academia, or if you get lucky on the job market.

Sorry. You should finish your PhD because it sounds like you've done a good number of good papers and deserve the degree already. Beyond that, you need to think about a market niche.