I think he's referring to pre-existing apps, though I'm sure he'd be happy to have suggestions (I know I would.) In this same vain, Twitter is, effectively, a

I think he's referring to pre-existing apps, though I'm sure he'd be happy to have suggestions (I know I would.) In this same vain, Twitter is, effectively, a super simple idea that seems to have at least taken to legs in adoption, though I have absolutely zero idea what they're doing for revenue.