Nothing... Seriously though not too much. The best thing to do is check out a spring Kelly park in apopka (about 30 min from universal studios) is awesome and great for hiking and swimming. Downtown orlando is nice to get away from tourists at night if you are into night life. Also during the day the surround areas have a lot of cool boutiques/restaurants/ art galleries. Mt Dora in lake county is beautiful to spend a day and just walk around, but it's a track from the attractions.
As for north Florida.... That's even worse.
South Florida is awesome with so many big city's so close to each other. You are bound to find something to do in Miami/ ft lauderdale or Tampa/ st Pete. almost 8 years ago
If you're a science geek, the Kennedy Space Center can be very interesting.
The other parks near Disney can be fun too. Universal is fun for rides. They have the new Harry Potter Park. Sea World might interest you too.
At Discovery Cove, you can swim with dolphins and other aquatic animals.
Have fun! almost 8 years ago