My first internbet connection was 14.4k dial-up, and I actually downloaded MP3s via Napster! When I got 56k connection speed went up to 40000 and something, but the actual download speed was still around 5 kb/sec.
In my old PowerBook I've got a built-in 9600k modem, never got it working though, since I upgraded to System 7.6 the TelePort software denies my machine being a PowerBook.
Cable is shared by 3 Macs, via a software router. Think about buying a hardware router though, then we don't need to have one machine running all the time.
Maybe I even get an acoustic coupler for my museum. 300bps max connection speed, not kbps!