Small LrC plug-in that enables a very specific workflow for rapidly applying multiple keywords at once via LR's keyword sets.
This will be mainly helpful for situations where you need to tag photos with 3 or 4 different subjects that might appear in the photos in different combinations. A typical example would be family photos with 3-5 different family members. Also, this plugin makes mostly sense when you tag your photos one after the other instead of selecting a bunch of photos at once.
In my search for the most rapid way to tag such photos I find the described workflow the quickest. However, your milage, or your style of tagging, might vary.