Is there any one place to go to get information about a U.S. citizen's emigration options?

People joke about leaving the country, but what are the options, really? I have no intention of leaving, but I've still wondered where to find out HOW one really would leave the U.S. I assume one could check out immigration policies for individual countries, but I can't find that anyone has compiled those on one site.

Just curious and thought I'd check with reddit.