I have a trilogy for you:
Buy a pack of pitches at VirtualPitchFest.com. You can use the pitches for shorts/features/pilots then, or hold onto the pitches forever, till you see some good opportunity... MEANWHILE, once you're a signed-up member of VPF, you can access their 'submit pitches' page, which lists all their members and what they're looking for. I use it as a foundation both for my own searches, and for pitching on VPF itself (when I have pitches).
I just checked, and there are some who are seeking 'shorts'.
Also, I agree with the comment about InkTip, though I think it's good for other things, too. Sign on for their 'preferred newsletter' (about $60 for 16 weeks of newsletters, each with 9-12 leads). I've seen lots of shorts requested there.
Lastly, there's no reason not to consider ScriptRevolution.com. The visitors can search for 'shorts' (or page length), so that would be one place to place those, or any of your scripts. You can post your script for download, or just post its details and tell visitors to email you.