Bookmarklets are bookmarks that execute JavaScript when clicked on, instead of opening a page. They can be used for a wide variety of small tasks that can add features or increase productivity.
Wall Zapper - Remove annoying paywalls and subscribe walls.
Distraction Free YouTube - Remove all the distractions from YouTube, leaving only the video.
Joke Generator - A basic joke generator. Note that this doesn't actually generate jokes, but rather pulls them from a human-curated database.
Edit Page - Edit any webpage.
Unlock Journal - Bypass the paywall on academic journals.
Change Video Speed - Change the video playback rate beyond the usual constraint of 0.25-2x speed.
Fast Forward - Fast forward any video at max speed (16x). Click again to return to normal speed.
Skip Video - Skip to the end of any video.
View Selection in New Tab - Displays the selection in a new tab. Preserves links, paragraphs and images. [Source]
Zap Cookies - Remove cookies set by the current website. [Source]
Latest Wayback Machine Archive - Opens the latest internet archive of a page. Useful when encountering 404-not-found or server errors. [Source]