Can Opener

Adds buttons for items that can be opened, learned, etc.

CanOpener

Adds buttons for items that can be opened, learned, etc. Very small and responsive.

Works on Retail and WoW: Forever from a single download — the addon detects which game it's running in and loads the right item list.

Movable buttons (hold right click and drag)
Automatically adds items as they get looted
Hides in combat
Character-specific settings
Lightweight, low memory footprint
Option to hide items with a level requirement you don't meet yet
Hides one-time items (e.g. profession knowledge) once you've already used them
Hides lockboxes unless your character can open them (Pick Lock or Skeleton Pinkie), with an option to always show them
Single-button mode: show one item at a time
Ignore list for specific items — Shift + right click a button to ignore it
In-game settings panel (Escape → Options → AddOns → CanOpener) with an Ignore List page

World of Warcraft: Retail (12.x)
World of Warcraft: Forever (1.60.x) — includes Forever-only openables; Retail-only options (like Rousing elements) are hidden automatically

Use /co or /canopener followed by a command:

rousing - Toggle showing Rousing elements (Retail only)
levelrestricted - Toggle showing level-restricted items
lockbox - Toggle always showing lockboxes (enable this if you open them another way, e.g. Blacksmithing skeleton keys)
single - Toggle showing a single button at a time
ignore <itemID> - Add an item to the ignore list
unignore <itemID> - Remove an item from the ignore list
list - Show all ignored items
reset - Reset the addon to the default settings

To request adding any missing items, open an issue or make a Pull Request.