OldGromm's Toolkit (GRTK in short) contains a number of smaller features.

Spec Change: Swap between two specializations with a press of a button. Assign a hotkey in the options menu or left-click on the minimap button.
Mount Macro: A menu to create your own macro to summon your mounts. Create your own list for ground, flying and swimming mounts + a modifier key shortcut for summoning a mount with a vendor NPC such as the Grand Expedition Yak.
Hearthstone Macro: Use all of your hearthstone toys in any order you want. You can use the Dalaran and Garrison hearthstone separately by using a button combination of your choosing as well.
Repair Message: Sends a message when you enter a dungeon, raid, delve, PvP match etc. if your gear is either partially or completely broken.
Victory Sounds: Play a custom sound whenever you defeat a boss or finish a mythic+ run. You can select from a number of PvP battle themes from the base game, as well as a few other tracks.
Reload Interface Hotkey: Why waste a second typing "/reload" in chat if you could just press a button on your keyboard? Assign a hotkey via the options menu (keybindings) and you're all set.

This add-on has been primarly tested with Midnight. Basic support for Classic exists, but some features have been disabled as they don't make sense.
In particular, the spec change feature has been replaced with a talent group swap feature.

The position of the various messages and menues can be changed via Edit Mode.

Available slash commands:

/GRTKO
Opens the settings menu

/GRTKB
Hides or shows the minimap button.

/GRTKS
/GRTKT
Activates the spec change/talent swap function.

/GRTKM
Hides or shows the mount macro menu.

/GRTKMA
Forces the mount list to move to the next entry.

/GRTKHA
Forces the hearthstone list to move to the next entry.

/GRTKRM
Shows a preview of the repair message.