Here is a list of addons that i use on a regular basis
LightHeaded - Ever Heard/use Thottbot or wowhead WELL This addons compiles comments from wowhead and implements them into this addon. So things from Quest locations, Quest tricks, Quest guides can all be obtained from using this Addon.
EQcompare - Compare equipped items to items in your bag/bank/hyperlink/chatframe
ARK inventory - This addon lets you catorgotise your inventory in as many ways as you want. Example: Have trash in one spot to allow easy vending.
You can also see your current bank AND your alts inventory and bank. This works well with Eqcompare if you have something you could use on your alt.