The tag notification is cool!! I've joined a forum that has that feature and it is really helpful in calling members attention. If I remember it correctly that forum use Xenforo? Plus they also has a qoute/reply notification feature which is also helpful especially when someone bumped a dead thread. You can also post a status on your profile(which not needed here 
).
Tag will be a great call for it. Nofication to promt your attention will be great addition. But goodluck to the admins if they were tagged most of the time. There should be atleast a restriction before adding this kind of feature ).
) .