This is an addon to sort items in your bags. It does not include any UI modification whatsoever, and should work in conjunction with any other inventory addons you might have.
To use, type /bagsort or /bs in the chat frame.
This addon will sort items in your bags using the following item attributes, in the order listed:
For instance if you have 2 epic item level 251 shoulder-slot items, it will place them next to each other in alphabetical order. You can think of the sort order as a "tiebreaker order" where items of the same type tend to be sorted next to each other first, then by subsequent "tie-breaker" sorting functions.
The addon will also sort items in your bank if you have the bank window open. Keep this in mind if you have your bank neatly organized by hand!
Finally, this addon will preferentially place special items in special bags. For instance, if you have an enchanting bag, enchanting materials will be sorted into that bag before being mixed in with the general items.