http://www.wdwinfo.com/wdwinfo/earlyentry.htm
Following is my slightly edited version of the above site's list-circa Jan. 2008
MAGIC KINGDOM - MORNING EMH Operating Attractions
Astro Orbiter
Buzz Lightyear's Space Ranger Spin
Cinderella's Golden Carrousel
Dumbo the Flying Elephant
"its a small world"
Mad Tea Party
Mickey's Philharmagic
Peter Pan's Flight
Snow White's Scary Adventure
Many Adventures of Winnie the Pooh
Space Mountain
Stitch's Great Escape
Tomorrowland Indy Speedway
Tomorrowland Transit Authority
MAGIC KINGDOM - EVENING EMH Operating Attractions
ALL OF THE MORNING OFFERINGS PLUS:
Big Thunder Mountain Railroad
Haunted Mansion
Magic Carpets of Aladdin
Mickey's PhilharMagic
Splash Mountain
Country Bear Jamboree
Jungle Cruise
Swiss Family Treehouse
Stitch's Great Escape
Pirates of the Caribbean
EPCOT - MORNING EMH Operating Attractions
Test Track
Spaceship Earth
Living With the Land
Mission Space
Soarin'
EPCOT - EVENING EMH Operating Attractions
ALL OF THE MORNING OFFERINGS PLUS:
The American Adventure (limited performances, see EMH Times Guide)
The Seas with Nemo and Friends
Journey Into Imagination with Figment
Honey I Shrunk the Audience
El Rio Del Tiempo
The Maelstrom
O Canada!
Kidcot Fun Stops
Also, a limited number of "Lands" may have certain shops open.
DISNEY'S HOLLYWOOD STUDIOS - MORNING EMH Operating Attractions
Twilight Zone Tower of Terror
Rock 'n' Roller Coaster
Star Tours
Jim Henson's Muppet*Vision 3-D
DISNEY'S HOLLYWOOD STUDIOS - EVENING EMH Operating Attractions
ALL OF THE MORNING OFFERINGS PLUS:
The Great Movie Ride
The Magic of Disney Animation
Voyage of the Little Mermaid
Playhouse Disney Live on Stage
DISNEY'S ANIMAL KINGDOM - MORNING EMH Operating Attractions
Expedition Everest
Kilimanjaro Safaris
It's Tough To Be A Bug
Discovery Island Trails
Pangani Forest Exploration Trail
DISNEY'S ANIMAL KINGDOM - EVENING EMH Operating Attractions
ALL OF THE MORNING OFFERINGS PLUS:
The Boneyard
DINOSAUR
Festival of the Lion King (Likely only one performance)
Primeval Whirl
Triceratop Spin
Kali River Rapids (seasonal)
Kilimanjaro Safari (closes at dusk, so might be available early-on)
Asia and Africa Trails (close at dusk, so might be available early-on)