Another afghan I made for Caron Yarns is the Christmas Granny (in the center) which was published in a Leisure Arts book called "Grannies Gone Wild". Although not free, the PDF download is only $2.99 if you want to check it out.
All of these squares, though, are 8-9". I found that I had to really push myself to continue going like I did with the 12" square. I've got plans to do more because you have all convinced me that 12-inch squares are the way to go.
Even if I don't make an afghan, they're big enough to cover a pillow form. What a fun way to try out new square patterns!