Someone put together a bunch of photoshops of 80s and 90s SF and fantasy novels, with new "more accurate" titles. I recognize all but a couple of them, and they're all amusing. (And a few are hilarious.)
The Oatmeal's "How to pet a kitty": I don't think i posted this it it first came out. But if i did, the internet has proven that you can't have too much repetitive cat humor.
The 18 Commandments of the Internet Comment Troll: Just a quick and amusing list of common internet troll behaviour.
The History of English in 10 Minutes: I think i first saw this over a year ago, but i don't think i posted it then and it's making the rounds again.
A couple people doing some pretty cool parkour, while dressed as Mario and Luigi, with special effects. I could have sworn i saw another similarly themed and just as well done video pretty recently, but i can't seem to find it now.
Game Launch Rock!: And finally, since the PS4 is coming out today and the XBox One is coming out next week, here is a public service announcement in the form of a Schoolhouse Rock parody about why you shouldn't be buying either one at launch.