I love Stack Overflow. But the sidebars can get annoying, especially the Meta and the Hiring ones. Plus, many a hour have I wasted browsing through "Hot Network Questions" because I saw an interesting English Stack Exchange post. And oh my god the Chat thing is so useless.
This extension cleans all that up. Get it on the Chrome Web Store. I wanted to keep the Related and Linked questions though - that stuff's useful.
Written in about 20 minutes in a state of anxiety-driven self-loathing for having wasted too much time on Stack Exchange when I should have been working on an Algorithms assignment. Relevant xkcd: https://xkcd.com/1319/