With the exception of Catwoman, I've really enjoyed every DC Showcase (the shorts which are often released in addition to DC Animated Films). They've been great for getting a nice insight into characters one might not have that much exposure to.
So this got me thinking about what characters future Showcases might do. I personally think Martian Manhunter would be a great idea. Let's here some others.
Edit: Please excuse the misspelling in the title - Showcase*