E-commerce is everywhere. Amazon was the first to become really profitable, and there are tons of companies that operate exclusively online. I think there is room for more, but the problem is that it is still too hard to pay for stuff online. When you walk into a store how hard is to pay for something? You literally just hand it over. If it's cash you get your change. The most complicated way to pay for something would be a debit card. All of a sudden you have to type in a PIN. Still not that hard.
Online you have to register at the site, then you have to fill out all your personal information, then a credit card number (with billing address). God forbid you should need to get something shipped somewhere because that adds a whole extra step.
Paypal makes it easier. You just sign in and your account gets charged, but it suffers from flaws as well. First of all it's centralized, which is scary should it go down. There's a reason why we have multiple banks. Second, it's takes for freaking ever to transfer cash into your paypal account. 5-7 days per transfer. WTF? Credit cards are easier to use, but what if you just want to pay for something in (the electronic equivalent) of cash? Finally Paypal isn't supported by everyone and they still charge sellers to use the service.
What we need is some new system that allows for easier payments for stuff online, that isn't centralized. Something like INTERAC but for the internet. Imagine it being effortless to pay for stuff online? Just enter your username and password and click pay.
An simpler online payment system would really vitalize the internet. It gives people an alternative way to support themselves without resorting to ads or sponsorship.