There are presently 3 FM satellites - SO-50 as you already mentioned, AO-51, and AO-27.
AO-51 operates on a schedule, since it has options for uplinks on 2m, 23cm, even 10m, and downlinks on 70cm or 2.4 GHz. Voice and digital operation are possible on this satellite, but at the moment it is set up as a simple FM repeater (uplink 145.920 MHz, downlink 435.300 MHz +/- for Doppler) and 9600bps telemetry downlink on 435.150 MHz. Schedule and more information at:http://www.amsat.org/amsat-new/echo/ControlTeam.php
AO-27 is 14 years old, and functions as an FM repeater for 7 minutes on afternoon passes over the Northern Hemisphere. The satellite switches the repeater on when it moves northward from approximately 29 degrees North latitude, and more information on the satellite can be found at:http://www.ao27.org/
An e-mail list specificallly for FM satellite stuff is at:http://groups.yahoo.com/group/fm-satellite/
E-mail me directly, and I can send more information your way. Good luck and 73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/