You can use them to highlight faces or other portions of your photos. You can put words in them or use them like little picture frames by attaching twine or ribbon behind them and using a brad for a hanger.
I've colored mine with sharpies - found a set of school wooden embellies in the dollar store and snatched them for back-to-school. Natural wood looks great too!
if the frames are too little for the pics, they work great as a base for embellie cluster - add a flower or a bird behind the frame and it will look gorgeous!