Perhaps this is evidence that myspace is good for something (research), or perhaps not...in any case, from someone's myspace profile I found this site which gives you a voice record module that allows people to leave you voice messages online:

You call the number specified and leave a message entering in the code provided and then it comes up online. Problems? Well, first, it seems that the number is long distance, which I suppose is fine since most cell phones have free long distance, but it would be nice if it was an 800 number. Second, the player is sort of ugly. And third, the comments are really in response to nothing in particular and there appears to be no way to control who leaves you comments (no filtering system). Still, its kind of interesting. Try it out, leave me a message...for no apparent reason.