WowAce

This feature is included in Baggins and other bag addons and I think it would do well here. By adding the ability to filter by text in the item description, you could have more complex and sane sorting systems.

Some examples:
'Type: Consumable - Food and Drink' AND 'Usable' NOT 'Description: Match any:"alcoholic"'
     Filters alcoholic drinks out of Food and Drink bag.
'Type: Armor - all' NOT 'Quality: Common, Uncommon' NOT 'Slot: Tabard' NOT 'Description: Match exact:"Use: Creates a soulbound"'
     Filters garrison mission armor rewards that have not been redeemed out of armor bag
'Type: Consumable - all' AND 'Description: Match exact:"Use: Increases" OR 'Description: Match any:"increased"'
     Creates a bag that includes all consumables which apply buffs
'Description: Match exact:"<Right click to open>"'
     Creates a bag for presents, bags, and other openable goods
'Description: Match any:"grants"' AND 'Description: Match any:"skill"'
     Creates a bag for items which grant skill ups
'Usable' AND 'Description: Match exact:"Cooldown)"' NOT 'Description: Match exact:" Charges"'
     Creates a bag with usable items that don't get consumed on use.