Acquisition, Acqlite, and Limewire all connect to the Gnutella network. There's also Xfactor which connects to FastTrack (Kazaa), Gnutella, OpenFT and Ares. You can search Macupdate.com for apps that connect to the Soul Seek network. There's no Mac app that connects to the WinMX network.
I haven't tried hosting my own content, but Gnutella generally seems the best to me. I've had very little success downloading with FastTrack and eDonkey, and would advise against them.
BitTorrent is a super way to distribute files, but you'd need to get the torrent file on a tracker where people can find it.