I'd wish there would be a browser extension that would find all the occurences of numbers with imperial units (like "40 feet" or "10 miles") and offered a metric conversion as a hovertext, or whatever. Just like this dumb, annoying Skype extension that converts everything that looks like a phone number to Call-By-Skype button, but without the dumb & annoying part.

It's hard for me, as well as probably for the majority of this planet, to easily visualize what the article is about, when everything is given in alien units (and constant CTRL+TABing to Wolfram|Alpha kind of breaks the reading flow).