California Games: the title screen music is a virtual re-recording of "Louie Louie" by Richard Berry.
Other observations within (the gameplay):
The Half Pipe stage music sounds like "I Can't Explain" by The Who.
The Foot Bag stage: sounds like "I'm a Man" by Spencer Davis Group.
Surfing: sounds like a re-write of "Wipeout" by the Surfaris.
Skating: sounds like both "Cars" by Gary Numan and "We're an American Band" by Grand Funk Railroad and, perhaps, "Sunshine Superman" by Donovan as well.
BMX: sounds like "Theme from Batman" by Neal Hefti
~Ben