One issue I've struggled with while trying to find my way around Drupal's Form API is that there appeared to be no easy way of putting input elements into a table. The solution is to create new form elements using the elements hook, the process of which has been modularized into the Form Table module. Unfortunately Form Table hasn't, as of this writing, published a version compatible with Drupal 6.
Modifying Form Table module to work in Drupal 6
Barrett Tue, 01/13/2009 - 09:30