Junk items -- items with no purpose but to be sold to a vendor for gold -- are now marked with a small gold piece. When it's time to shed your vendor trash, you can now see at-a-glance what you should be selling.
In addition, everyone's bank now has a dedicated 98-slot reagents tab for crafting materials and other miscellany. Certainly, that's a better solution than using numerous profession-specific bags such as herbalism's Hyjal Expedition Bag. The reagent tab comes with a Deposit All Reagents button, allowing you to deposit your array of herbs, ores, or whatever else you may have with a single button press. The button is also useful if you're not sure what does or does not qualify as a reagent. If the button takes it, you're golden. If it doesn't, it isn't a reagent.
A screenshot of the reagent tab is included below if you want to see it for yourself, but let's be honest -- it's a grid of empty inventory squares. I think we can all visualize that pretty well.