If you're using Revit 2014 and have tried to add the Callout tool to your Quick Access Toolbar (QAT) you've been turned away, rejected, sorry no you can't do that here... Sorry, applying Web Update 3 doesn't fix it either.
Subtle and minor it may be but stuff like this frustrates users. ...and I was sure it was possible. Oh right, it's working in Revit 2015. One more subtle reason to upgrade.