I have created a video on Youtube of what happens if a debt limit is enforced in a modern economy (spoiler: bad things). It is based on a simple Stock-Flow Consistent model.
The Youtube URL in case the above embedded video does not work: http://youtu.be/928QLfMlBvM
This video is a bit of a technology test on my part.
A longer explanation of what is happening within the model (including simplifications made) is given in this blog post:
as well as here:
Also: I have just set up a Twitter account;
(c) Brian Romanchuk 2014