I've been meaning to spotlight this one for a while, but never got around to it! Way back in early December, graphic artist Mixermike622 started up a crossover pony tumblr based around another hub cartoon that many of you have probably seen by now. Dan Vs. follows the life of an angry guy named Dan, who hates just about everyone and thinks everyone hates him.
The actual tumblr explores his exploits in Ponyville, interacting with the mane cast and various other ponies in ways only someone of Dan's level of insanity possibly can. The creator also does an amazing job of filling the role of Dan, and barely ever drops character.
Unfortunately, due to computer trouble, he was unable to update for quite a while, he even gave up at one point. Fortunately for you, the archives are chock full of awesomeness, and the video above was released just yesterday, so even if he doesn't continue it, there is still a ton of content from the last half a year to dig through.
Anyway, check the blog out here, and the archive here if you need to catch up!