My concern is that since it has nothing to do with building or modifying furniture it's a little suspect. However, I think this community could answer it without stretching much.
"How do you calculate load capacity for a large piece of furniture, like an entertainment center or china cabinet?"
Given a particular material and structure, joints, etc how does one calculate what it can hold safely?
UPDATE: I really am interested in learning more about this, so I asked the question to match an actual project I'm planning for so it hopefully fits the spirit of the site. I built a "shelving unit" out of 2x10s while in a dorm - would have been nice to know that was a massive overkill back then :) And if it should be closed, that's fine too.