LegionBarKeeper
This Addon is some kind of an ActionBar Saver but targeted at automatically syncing Actionbar for multiple specs of one character.
You can configure each SLOT in an Actionbar to be synced or not.
NOTE
This is an "early access" release. While i consider this addon as "mostly ready" and using it myself already its usage may change in the future.
Basic Usage
Type /lbk or /legionbarkeeper to open the configuration. You will see the 10 Actionbars on the left side and on the right side you'll see a set of action slots. The first 2-4 (depending on count of talent specalizations available to your class) columns represent the "current" state of your actionbar. The checkboxes in the "Override" column set if a certain slot should be synced between specs or not. In the last ("with Action") column you can place the actions that should be used for syncing. check the "Override" column for the slots you want to sync and place the desired action in the "with Action" column. you can either drag from your actionbar, inventory, spellbook or simply from the first 2-4 columns.
Slots that are synced update thier "with Action" column when you put a new action into that slot, you won't need to open the option to set another item/spell to sync for that slot.
More docs to be done
There will be a more advanced "how to" guide including ingame tips at a later point.
Feedback / Issues / Feature Requests / Support
I'd be happy to get feedback as well as Issue reports or Feature requests using the curseforge issue tracker.