I got this information off of
Disneyland's site (I was curious, too!):
Disneyland® Park
32" (82 cm) or taller — Accompanied by Another Rider 54" or Taller
Autopia, presented by Chevron
35" (89 cm) or taller
Gadget's Go Coaster, presented by Sparkle®
Matterhorn Bobsleds
40" (102 cm) or taller
Big Thunder Mountain Railroad
Space Mountain
Splash Mountain
Star Tours
46" (117 cm) or taller
Indiana Jones™ Adventure
54" (137 cm) or taller — To Ride Alone
Autopia, presented by Chevron
Disney's California Adventure® Park
36" (91 cm) or taller
Tuck and Roll's Drive'Em Buggies
40" (102 cm) or taller
Jumpin' Jellyfish
Soarin' Over California
The Twilight Zone Tower of Terror™
42" (106 cm) or taller
Grizzly River Run
Mulholland Madness, presented by Alamo
Redwood Creek Challenge Trail
48" (122 cm) or taller
California Screamin'
52" (132 cm) or taller
Maliboomer