Having an option to "Lock Tags" so that new tags cannot be accidentally created would be great. A simple on/off switch so that when I want to add a new tag I can, but when I'm happy with the way things are I don't accidentally create a #workk or #wokr and #woork tag when I'm trying to use #work - especially since as soon as I type the tag out, it's created whether I made a mistake or not. Allowing me to lock my favorite tags in place until I'm ready to add a new one would be a HUGE help.