http://www.mydd.com/comments/2006/11/4/175848/845/3#3
"If you have voice mail through your phone company (in other words, you don't have an answering machine in your house), sign up for a free account at GotVoice.com. This will let you download those voice messages and save them. The free account is limited, but it's good enough for occasional use. Basically, if you hear a message on your voice mail that's worth saving, don't delete it. Hang up, then log in to your GotVoice account. Their service calls in to your voice mail, listens to and records your messages, then presents the audio clips on your browser so that you can listen to them online or save them to your PC. At that point, you've got a permanent copy of the message. GotVoice works with the voice mail services of most residential and cell phone providers. I don't use it often, but it comes in handy once in a while."
http://gotvoice.com/