I'm big into png overlays, it transforms boring old images into a richer looking design.
Take a look at this variation:
To create a png overlay is quite simple, take the dimensions of the images, in this case 140px square, then create your png overlay in photoshop, give it a bevel effect, drop shadow or even a piece of sticky tape.
Then in your markup which will be in the module template files. Tip: use Dreamweaver and search for the markup, in this case "<div class="sys_file_search_pic">" as this is the markup in the template file.
Then add your div, in this case "<div class="event_overlay"></div>". For this markup you will need to set the positioning to absolute and the image pathe, like so:
.event_overlay {
PlayBox Design | Taken from Event.