How can I handle exceptions on the front end So I have some exceptions being caught in a plugin, and have to assume that in some cases a 500 error is going to occur at some point.

How can we set up Craft so that a server error displays a template rather than the default message display (assuming devMode is OFF)?

This would be something we'd want working across the whole site, not just on one plugin.
If you put a 500.html template in your craft/templates folder, then that will get displayed on the front end when a exception bubbles all the way to the top.  The same will work for other HTTP status codes as well (404.html, 503.html, etc.).