So Mozilla has jumped on the "let's teach everyone to code" bandwagon and among other things created this. Basically, it's a tool that allows you to not only look at elements on a webpage but also edit their values (text, images, hyperlinks, etc) and publish the results. Yes, it's not a HUGE technical achievement, but it's a nicely integrated way to have some fun.
...and by "have some fun" I mean "tear the Internet a new one". I'd like to see anyone here can create any amusing parodies of existing websites by replacing whatever you deem appropriate. Here's what I came up with with following around for about 6 minutes:
