2 addons that I really really like are

1) bagon (makes one big bag)
2) bankstack : sorts/organizes the contents of your bags for you.

Bank stack makes is so all your like items end up in the same area. So all your food buffs are together as well as weapons/armor or quest items. To activate bank stack just type in "/sort". After this is done then all your toons should have along the same organization. This is particular helpful in finding "use:" quest items.

This and something that auto sells gray items for you (jamba will do this).