Chrome/Firefox: Paginated posts are never fun to navigate through, because they require an excessive amount of clicking. PageZipper is a Chrome and Firefox extension that turns multi-page posts into one simple, endless scroll, complete with keyboard navigation.
We've mentioned PageZipper before when it was just a bookmarklet, but the extensions get it out of your bookmarks bar so it doesn't take up too much space. When you navigate to an article that has multiple pages, like a long-form piece or a gallery, click the PageZipper icon, and it turns it into an endless scroll. You can then navigate between pages with Ctrl+Down and Ctrl+Up.