Myoats is a place where you can create simple or complex designs, shapes and patterns.. The designs that you create can be:

• Downloaded as an image.
• Downloaded as a transparent png.
• Saved to your personal account, which allows for editing and re-saving.
• Made into a wallpaper
  

Some interesting works displayed on the site.  Check it out.  http://www.myoats.com/create.aspx