From diamondPants :
Create your own Pixel Art by converting the pixels of any image or picture to Minecraft blocks. Convert any image in to an image made of Minecraft blocks. Supports jpg, png, and bmp. Not sure what that means? Don’t worry about it. Set a maximum height of either 30 or 60 blocks. Export to schematics for use in MCEdit or other tools. Configure which blocks can be used. Don’t want to use gold? Turn it off. Supports any texture pack, including HD. Choose between a picture using the sides of Minecraft blocks or the tops of Minecraft blocks. Supports massive images. Tested on images as large as 6000 x 4000.