New words get invented all the time. Now everybody knows what "blog" and "twitter" refer to, but who came up with those words?
Let's start with blog. As most of you know, it's short for weblog. The word weblog is from 1998, invented by Jorn Barger, and it was shortened to blog by Peter Merholz.
The word twitter, as referring to birds, is from the late 14th century, but the microblogging service is only from 2006. Twitter was created by Jack Dorsey, Evan Williams, Biz Stone, and Noah Glass, and the original name was twttr, inspired by Flickr, but they changed it to Twitter. (A wise move, because how annoying is twttr?)
Zuckerberg's Facebook was originally Facemash, a website that placed two pictures side by side and allowed users to choose the hotter person (wtf?). Yeah, kind of glad I'm not on Facebook.
Internet, from 1984, is a shortened version of inter-network, like linked computer networks. The word inter-network was used in the seventies, even before they could actually link the computers together.