Hey, there! I’m out of the office this week, but my Twitter signal is always on. Seriously, I’ve got robotic wonder thumbs! (No, not really.) I never fail to tweet fascinating stories about how people can win big with their marketing efforts. So, until I’m back at my desk, won’t you follow me [LINK]? Whether you follow me or not, I’ll get back to you as soon as I can upon returning to my desk on [DATE].
A word of warning: These greetings will not do you any favors if you're in the midst of a job hunt or work in a conservative industry. Always remember your target personas. If there's a chance they won't appreciate your sense of humor, opt for a straightforward greeting instead.

This is a general notice informing you of the absence of [NAME] until [MM/DD]. [NAME] has chosen to exercise his right to partake in the traditions of a certain holiday which may or may not be a denominational or non-denominational.
Yes, mine (for external e-mails) typically says somethingalong the lines of “I’m out of the office until [date/time] and messages to this address are not monitored in my absence. I will respond as soon as possible on my return. If your message is urgent, please re-send to my assistant [email address] or telephone [assistant’s number]” Internal it will usually just say “I’m out until [date/time] pass any urgent enquiries to [co-workers] ” although my assistant and a couple of others have my home number and personal e-mail so can get hold of me in a genuine emergency, and I will sometimes speak to them in advance if I’m willing to lower the bar on what amounts to an emergency, but I would not expect any of my employees to do that !