I found this interesting one-page summary of how a bill becomes a law in the US. It’s pretty straightforward but I imagine there are a lot of things that factor into the process that is not covered on this page:
http://www.votesmart.org/resource_govt101_02.php
Of course, those of you who are old enough to remember this one, already know how a bill becomes a law:
Schoolhouse Rock- How a Bill Becomes a Law