Buying Digital Goods online : A company selling vpn's/proxies/social media marketing, are more likely to use bitcoins rather then fiat cash .Why ?Because its easy! Who would want to pay additional taxes and bank service for online payment setup when you can just have everything automated for few digits ?
Porn Websites :Though it belongs to Digital Goods category ,it has its special relevance .Privacy .Why would some has to leak their bank details online to buy the service ? Bitcoins are transparent and anonymous to reveal anyone's identity .
E-Commerce :The way e-commerce is taking over hardly you can find anything which is not available online.As the number of people using bitcoins rise,the big giants will soon start accepting them.It has already begun on the markets coming out of Europe.
I'd like to online gambling where Bitcoin can have a huge impact! Sport betting, online casinos, online poker, prediction markets etc.
Bitcoin can also create completely new ways to generate income online. I'm thinker about youtubers, twitch, live podcasts, live streams (online lectures offered by schools or teachers), bloggers and many many more.This way people will earn Bitcoin!!