The mod I made and am still working on is SpellBook Abridged for WoW Classic. Right now, I am trying to keep the Spellbook normal, but I added a filter to select between showing all spells and showing only the highest rank of each spell. On my last update, I also included a function that replaces spells in the action bars when a higher rank is just learned, but only the previous highest rank, not the rest.
My current objective is to help improve visibility of spells that are usable in the current stance or form, a way to help druids quickly see which spells work in which form (and warriors if applicable). Basically, I am looking for suggestions on how to display the spells that are not usable in the current form. I am also working on ways to identify the spells without keeping a library in the addon.
I am also looking for other suggestions to make the Spellbook nicer in WoW Classic without a significant overhaul of the existing Spellbook design.
My current limit is the Spellbook addon has taint bugs when open during combat. I took the simpler approach and have the Spellbook close and not open during combat.