This is for fans who do not wish to pay for webcasts or audiocasts of this weekend's games but who are looking for free radio broadcasts.
Both opposing teams broadcast their games on local radio and both stations have free streaming. Note that stations sometimes do not stream certain sports broadcasts so there's no guarantee that these streams will be available for the Cal games, but it's worth a try:
Cal at Old Dominion, Friday 11/30, 4 pm PST: Here's the link to ESPN 94.1 FM.
Cal at Duke, Sunday 12/2, 11:00 am PST: Here's the link to WDNC-AM 620. (I was able to listen to tonight's Duke at Michigan game at this link, so I'm optimistic that it will work on Sunday.)