Some years ago I played World of Warcraft. This repository contains the UI addons I wrote. They almost certainly do not work with the modern game client.
ActionUI replaced the micro icons on the right side of the main Blizzard action bar with an extra set of action buttons, giving more space for spells and macros without completely replacing the default action bars.
The micro icons themselves were moved to a menu that dropped down from the minimap.
ChatWindowLayout added a slash command that moved the chat windows into the exact position I wanted them in.
CraftUI contained a database (scraped from wowhead) of crafting materials, the recipies that used them, and the skill levels at which recipies using that material would grant a skillup.
It used this to add this information to item tooltips for crafting materials, meaning you could more easily determine which items were still useful to you (or useful to sell on the Auction House), and which were no longer required and could be safely vendored.
StanceBarReorder allowed you to drag and drop the warrior stances or druid shapeshift forms on Blizzard's built-in stance bar. I think the ordering of the druid's shapeshifts was bothering me.
I have uploaded these for posterity - I had a lot of fun with WoW, back in the day!