Paper princess has listed the sites I use. But once you have the basic shapes you want, you can make 100's of different ones with simple changes. One of my favorite is to make a band at the top slightly more narrow and pleat the bottom into it. This give it a bit a fullness at the bottom and a less boxy look. But, patchwork, pockets, appliques, full straps, messenger bag flaps, these all make unique bags from one pattern.