Many cast members get what are called silver passes, which are like annual passes with a couple of black-out dates (no entry on Christmas Day, New Years Day, Easter, 4th of July). My husband has been getting one of these each year, and this year I got my own silver pass for the first year.
The silver pass entitles us to four park passes each day though, not just one. So on our next trip, we're getting each of our moms into the park for free each day. You cannot get the park passes in advance though, so it means that each day we have to go guest relations to get passes for that day only.
As for discounts on other passes, it's not a big discount (probably because we already get silver passes!). I think we got a $10 discount at
Disneyland (our silver passes did not work in Disneyland all summer this year). We looked into purchasing tickets for the rest of our crew, but I don't think it wound up any cheaper than the regular pricing since they've changed the ticket packaging system.