This looks like another incredibly useful service: Air America Radio

Air America Radio's Public Voicemail - 1-866-217-6255

Call the toll-free number above, enter your everyday phone number, and then record a message. Other people who know your everyday phone number (even if it doesn't work anymore) can call Emergency Voicemail, enter the phone number they associate with you, and hear your message.

You can also search for messages left by people whose phone numbers you know.