I've heard about the amateur satellites for years but never tried to listen in. I guess my assumption was that a directional tracking antenna would be required, but it seems with at least a recent device, AO-51, that's not the case.
It only passes over for a few minutes, when it does, and you find out where it is here. I entered latitude and longitude for Sydney (34 south, 151 east) and clicked predict.
This morning there was a pass that looked perfect so I wandered out into the back yard with a hand-held receiver tuned 435.3Mhz and with the antenna positioned horizontally, I was able to hear snippets of people talking.
Sorry about the poor quality, this was recorded with a little dictation recorder held up to the speaker.
Anyhow, this is very encouraging. I understand it's even possible to talk back through the satellite with a hand held. The uplink is on 145.92Mhz.
Because of doppler shift, you have to tune up as the satellite approaches and down as it runs away.
There's a nice page of suggestions on the Amsat site.