I haven't seen one but if I do I'll pass it along. I agree that it is pointless for you or them to memorize it. And I'm sure your class thanks you for not making them.
How about taking a screen shot of one online in a landscape position. Then in a Photo Editor program, rotate, it clockwise 90 degress and then resize to 360 by 480. Save that file and load onto BB Memory card in photo folder. Now, you can look at it and zoom in and pan around to see it.
You could also Wiki Periodic Table and I believe there is a snaphot there. If you are looking for something more dynamic i.e. click on a element and more info pops up - that could be cool.
I have the first 3 rows pretty much memorized just because I've had to use them soooo much in the past 8 years. But a PT app would be pretty frakking sweet.