Yahoo! - Poll from very late 20th century

Arguably graphic design. Compared to the 90's it has been greatly popularised; so many people nowadays produce digital pictures and 3D models online, be it artwork or assets for games and mods.

It also made the most noticeable advancements, as far as graphics are concerned. Remember when this was considered mind-boggling graphics?

Books. Literature has had a massive revolution in the way people can publish and spread their ideas and stories. Some of the largest digital archives hold tens of millions of stories from fanfiction to original works and publishers will publish anything they can get their hands on. Everything else has hit a block as major corporations and the entertainment industries have tried to control how wide spread certain things can be. Now only those with money can do the last four without being stopped.