[mariust]

Are you looking to learn new skills or to make money? Learning something new is not going to bring you $50 / day now, but on the long run yes it could turn down to $500 / day or more. With that said I would suggest looking into the mobile industry iPhone and Android for now (the other mobile OS are not worth the time and effort, the manufacturers will create a true OS pretty much soon - if they wake up from they're dream " We have a mobile OS").

A lot of the content on the web today is getting much attention from smartphones, so there is a ton of potential out there.

Hope this helps