1. With inventory open (onscreen with a merchant), hold shift and use the cursor to wrap a freeform box around whatever loot you desire to sell. An additional click or sale hotkey should follow this action to fulfill the sale. Obviously this idea could manifest through different commands than I've proposed, but still a potential idea I think.
2. A hotkey or button to sell all non-magical inventory items. I think it would be best that this would be proceeded by a "sell all NM loot for $xxx?" sort of confirmation, less to prevent accidental sales and more to give the player just a short moment to recognize the value they'll be incurring from the sale. I think, whether knowingly or not, players would appreciate seeing the numerical value of their sale, just for a quick mental twinkle. In fact, I think that this same confirmation cue should arise following my first idea as well.
So, since Blizzard actually listens to us, I figured I'd share these thoughts. Thanks for reading...what do you think?