Firefox/Chrome: Wikipedia's footnote system isn't the best — constantly clicking up and down the page is a pain, and it's easy to lose your place. With this simple userscript (or bookmarklet), you can view footnote text by mousing over the footnote inline.
Not only is it annoying to constantly click away from what you're reading, but it's always difficult to tell which footnote is highlighted after clicking on it, and there's a lot of small text down there to confuse you. Instead of jumping around the page, load this user script into Chrome or a Greasemonkey-enabled Firefox to get a link pop-up when you hover your mouse over footnotes. It's not unlike those ads that pop up when you mouse over links on some websites — except these don't stick around after you've moved your mouse (and they're actually useful).
Wikipedia Footnote Popup Script is a free download, works in Chrome or Firefox with Greasemonkey installed.
Wikipedia Footnote Popup Script [no.good.at.coding]