Different types of pouches would be fun. Some ideas:

herbalist's pouch: Stores plants found using herb lore
apothecary's pouch: Stores plants found using poison lore
alchemist's pouch: Stores vials

These pouches would work a bit like ingot chests do; they sort the different types into their own categories with a numeric amount.

And then a general purpose belt pouch, for small odds & ends like lock picks, maybe a knife, soul gems, sangor key, etc. Little things that would be nice not to clutter your inventory with.