Content Cherry-Picking
You know how it is when you write a feature length screenplay: Your script is full of tasty morsels but you can't remember where they all are. Wouldn't it be nice to be able to flag all those bits of killer dialog, lean scene description, key scenes you would hate to lose?
Today's software doesn't do much to help you here but the simple addition of way to flag your script 'cherries' would be useful to find them/remind you of them later or to quickly zero in when pitching your script.