Love the plug in but I've seen two things that could be added to drastically improve it.

First suggestion: The "this building is protected" message is perfect for knowing a building is protected, but what about when a building is taking extra damage? Quite a few servers make buildings take extra damage when a player has been offline for long enough. An optional message for a building taking extra damage would let players know just how much damage its taking.

Second suggestion: The plug in is a bit abuseable in the sense that some one can log off when being raided to try and start the protection and foil an in progress raid. Adding raid detection would prevent this. Something like, a building taking damage from players while the owner is on starts a "raid timer". While this timer is active, the protection will not start even if the owner logs out. Each time the building takes damage, the timer resets.