I created a few, but I stopped when I realized I couldn't easily load them for everyone else with a partial cui, unless I'm missing something.
If memory serves, each user would have to transfer them to Main in CUI editor.
If you're sticking with native options, transferring them is the simplest option, second would likely be custom Contextual tabs (which I've not yet implemented personally).
FWIW, these are incredibly easy to implement via .NET API; how many are you after, and what do you want them to do?
Cheers