I've just put a set of photomasks in the store! It's a set of five different masks.
They are so much fun to use! You can clip them to your photos, of course, but have you tried clipping them to papers and then using your blend modes? Or clip to a paper and use as a mat or frame for a photo. Or try filling them with a color or texture. Or even load up some styles (glitter anyone?) and apply some great effects!
Just play and have fun with them!