Spritecraft is a simple application that allows you to turn any image into pixel art made of Minecraft blocks.
It's really easy to use; just upload an image to Spritecraft (jpg, png or bmp), define the maximum height of the final image (30 or 60 blocks) and click the "Create Minecraft Blueprint". You can save the created image in png.
A word of warning: avoid uploading very detailed images, as the end result can be poor.
Download Spritecraft 1.1.3 in Softonic