Usability Improvement: organizing dropdown select boxes that list fields

There are several dropdown select boxes that list fields in CiviCRM (Import, Export, Search Builder etc.). These are very difficult to navigate since they list so many different options. They are listed in groups according to field type, but it's not obvious and it's still hard to follow. Dropdown select boxes can be better organized using the optgroup element
http://www.w3.org/TR/html401/interact/forms.html#edef-OPTGROUP

See the screenshots for examples