It would be pretty great if Forms allowed admin users to add more items to the "toolbox" pane in the form designer. Currently we use Custom HTML fields, but there's a lot of custom elements we use over and over, and it's a pain in the neck to copy/paste the markup from an external source every time. It would be great if we could just define them somewhere in the Administrative section and make them available to various processes, similar to how Data Sources work with lookups.