An Intro to World of Warcraft Addons (Part 4)

In Part 1, I discussed what an addon is and how to install one via Curse.  In Part 2, I discussed essential, non-intrusive addons that improve general gameplay.  In Part 3, I discuss addons with a moderate impact on user experience, specifically in combat, that I still recommend to improve the gameplay experience.  In this part, Part 4, I discuss data/UI management addons that I find very helpful, but your mileage, of course, may vary.
Altoholic
Altoholic allows you to quickly see how much gold you have on each character, and search characters for items, handy for locating who you left those heirloom capes on.  It also shows you how much rested XP you have on each, and will warn you when mail is about to expire.

Titan Panel
You have to see Titan Panel's page to fully understand and appreciate it.  It's a quick bar at the top of your screen that gives you multiple types of information, available via additional add-ons.  It's not for everyone, but those who use it swear by it.

Combuctor
Combuctor is an inventory management addon, plain and simple.  It allows you to search inventory, automatically pull up a tab that will only show quest items or equipment.  It's best explained with a picture:

The best part?  It has completely customizeable add-ons that create or enable different tabs, especially handy for managing professions.  Here are a few I recommend to everyone:

• Combuctor Scrap: Identify all those junk items.
• Combuctor Cooking: Particularly handy especially if you don't cook!  Quickly vendor those cooking items.

Part 5 addresses questing add-ons.