You may additionally want to bear in mind that people might be calling you from their cellphones, and a long message can use up someone’s valuable cellphone minutes. Some voicemail systems have the option of pressing a key like the pound key to immediately start recording a message; you may want to consider the funny or long message only if you have this option available to callers. Another point of consideration when recording an answering machine greeting is who is likely to call. If you’re job hunting, for instance, you may want to drop the funny salutation for a while, and use a more standard and businesslike greeting, unless you’re applying for jobs as a comic. Is Amazon actually giving you the best price? This little known plugin reveals the answer. Some answering machines utilize cassette tapes.
In all there is plenty to consider when you’re recording an answering machine greeting. If you’re aiming toward a more secure home, you can use a very basic message. If you are really funny, and friends and family mostly use the phone line, maybe funny is the best way to go. For businesses, stick with the bare facts that give enough information to callers about when their call is likely to be returned or when they should call again. Tricia Christensen

A secretary in a doctor’s office creates a voicemail greeting that says, “If you have a scheduled meeting with us, we could use copies of all your medical documents from last year, so come prepared.” Using the word “could” gives patients the impression that they don’t necessarily “need” last year’s documents. See the difference between “could” and “need”? Your word choice can impact a future meeting significantly. If you want a customer to perform a specific action, you need to pay close attention to how you express your calls-to-action.
I've assembled this list in mid-nineties from the messages that people were emailing around. As far as I know, the author of this list is unknown.