As if there weren't already enough reasons not to use out-of-office replies, here's a new one I haven't seen before (from a web design company, I think):
I am out of the office until Monday, 9 March.
For LargeCorpA, please contact Person A at firstname.lastname@example.org.
For LargeCorpB, SmallCompany1, or SmallCompany2, please contact Person B at email@example.com.
Well, I now know several companies who are clients of this web design company that I didn't know before. So, there's a nice corporate info gathering trick -- send e-mail to known addresses at your competitors on a regular basis (especially during holiday-prone times, like school holidays and Christmas/New Year) and see if they'll give you lists of their clients for free, like this helpful person has.