I can't stand out of office auto-replies.
I send a message to 10 people and 3 back. I don't care that you took off on friday.
It would be great if when you send out an email you can tack on #noOOO or something like that, and the auto-reply system will not send those back.
Or maybe reverse it and say #yesOOO and OOO messages will only be sent when people really want them (which in most cases will be never).