... and JQuery. For example, JQuery's "select2" combo box can be adapted quite easily to do what Access "find" combo boxes do, using Ajax.
Two things are essential: nested subforms, and the need to make this very robust for the average non-professional IT person to use (such as myself).
Perhaps using Aptana and maybe BlueGriffon to develop simple "wireframes" (HTML tables) for forms ... and then drop in components which are then tweaked.
Any serious people think it's got legs?