OK, where to begin...
At Epcot they are testing Mission: Space - Check with guest services and they should be able to tell you if it will be open. The official opening is still weeks away, so there are no guarentees. This ride is the supposed to be the most intense ride WDW have ever opened.
Also at Epcot, go to the America Gardens Theatre and check out the World Music Concerts.
At Universal there's the new Shrek 4D and the Jimmy Neutron ride too.
Kong was closed for good last september, is bing replaced with a Mummy rollercoaster, but that doesn't open until 2004.
Also at USF, near the twister ride is a regualr show featuring the Ghostbusters and Beetlejuice.
Look out for a ton of new and updated characters at USF. They had a revamp on them last year.
Tarzan Rocks at Animal Kingdon. Great rock show if you liked the music from the film. Also the Primeval Whirl in the dino kingdom at AK.
Make sure you check out the Indiana Jones Stunt Spectacular. There are rumours that it will soon be removed.
Hope that gives you some things to try.
12 weeks to go 'til our next 'World' visit.