Of course! There's a lot of things to do in Universal for a 3 year old.
IoA:
Suess Landing: all rides/attractions here. Cat in the Hat, Suess Trolley Train, If I Ran the Zoo, One Fish Two Fish, and Caro-suess-El. Also, the Grinch, Cat in the Hat, Things 1 and 2, and Sam I Am and Guy are there!
Lost Continent: Depending on how tall your kid is, there's Flying Unicorn, a very cute and very good kiddie coaster. (Me and my friend went on it this past summer-we're 14!)
Jurassic Park: Only thing here would be Camp Jurassic
Toon Lagoon: Olive Oyl and Popeye are here. Also, fun to run around in the fountains! And Me Ship, The Olive is a GREAT place to run around and check out the views (think of it as Universal's version of Donald's Boat in MK)
Marvel Superhero Island: Spiderman and other Marvel Super Heros are here (ie Wolverine, Storm, etc), as well as some villians (Hobgoblin). No kids rides here.
Confisco's in Port of Entry has a character breakfast with Cat in the Hat, Thing 1 and Thing Two, and Spiderman (possibly others too).
USO: Shrek (no height requirement), Jimmy Neutron (stationary seating. MUST DO IF YOUR CHILD IS A NICKTOONS FAN!), Animal Actors On Location, E.T., Fivel's Playland, A Day in the Park with Barney, Woody Woodpecker's Nuthouse Coaster, and Curious George goes to Town. Basically, all of Woody Woodpecker's KidZone. Characters here are Dora and Jimmy Neutron (by Jimmy Neutron ride), Woody Woodpecker, Curious George, The Man in the Yellow Hat. Also, this past summer characters from Madagascar were there, as well as Scooby Doo (and the rest of the Mystery Gang). "Live" characters include Lucille Ball, Marilyn Monroe, the Blues Brothers, and Laurel and Hardy. Character dining here? I'm not sure. I think there is.
Glad to be of help!
