Before I get started, though, let me answer the obvious question: Since most forms are perfectly happy with a single submit button, why would anyone ever need two (or more)?

The best way to explain such a need is with an actual example from the last project I worked on. In that project, I was tasked with building an inventory system for a book-lending library. The book titles were all stored in a database, and administrators could use a browser-based interface to view the record for any book and then perform one of four actions on that record: check out to a member, check in from a member, mark as missing, and mark as sold.

Hmmm, I never came across a time where I needed more than one submit, but I guess those times do exist.