Unfortunately, I occasionally visit Twitter. It’s unfortunate because fully half of their website (the right half) is now devoted to bullshit nonsense I have no interest in seeing. Luckily, modern browsers let you override bad website design! In Google Chrome on Mac OS, you can open your Custom.css (typically in your user folder, under Library, Application Support, Google, Chrome, Default, User StyleSheets) and paste in the following:
// Twitter right-hand side bullshit
#page-outer #page-container .dashboard { display:none; }
#page-outer #page-container .dashboard .component { display:none; }
#doc #top-stuff { display:none; }
Problem solved!