For possible financial gain: Web applications. Lots of them, most will fail as with mobile apps, but say I could do one every month or two, that's 12-24x the am

For possible financial gain: Web applications. Lots of them, most will fail as with mobile apps, but say I could do one every month or two, that's 12-24x the amount of chance of success than building one substantial well thought through, maybe unsellable thing. None financial: I'd like to build robot or a virtual personal assistant (see film 'Her')