"Disguising" the player as a mob

Is there anyway I could "disguise" the player as a mob? I've seen the sethbling videos of his 'goat simulator in minecraft' game, but I'm pretty sure that was done with bukkit plugins. Is there anyway I can achieve this in vanilla minecraft? I already know that I should have a command block with this effect in it to start off, to make the player invisible, but I don't know where to continue..

//Have a constant redstone loop going for this command block
/effect @a 14 240 372000

Solution 1:

Here is a link to a video demonstrating and giving a tutorial of this: Minecraft: Disguise as a Mob in Vanilla

This method seems to work fairly well judging by the video. Keep in mind, knowledge of command blocks is definitely recommended as they can injure your world if not used correctly.