BankItems

BankItems is a World of Warcraft addon that allow you to see your bank items anywhere in the world, to see bags, equipped and bank items of your other characters or the content of your guild bank (based on the content last time you did visit it).  It also remember mail content.

It also put in the tooltip the numbers of that items you have in your bags and bank.

I recommend it.

I use it with BankItemsFu

* The screen capture is not mine. It is the one provided on the Curse page. *