I've looked for this myself, and to the best of my knowledge, no equivelent exists for the Mac. For those of you who don't know what it is, MyTunes lets Windows users downloard shared music on a network. I beleive this feature used to be part of iTunes, but Apple had to block it because people were using it to illegally share music. I don't even really understand this argument because I thought it was okay to share music with a couple of people (i.e. lend a friend a CD even though you already have a copy of it on your iPod). Isn't this the same concept?