I've also run across the big vertical break between submit buttons from different forms on a page. One thing I've done (which is far from optimal, but looks better than the big gap) is to stick the buttons in a table, each in its own <td>. This at least gives the illusion of a row of buttons.

The approach of having one main script dispatching calls to various handlers sounds like a good one.. I just wanted to make sure and point out the performance benefit of not having to parse 2000 lines of code to then only execute 20. I've seen this done way too many times in beginning CGIs.