I'm not sure if you have kids or not, so some of these may not interest you, but this is what comes to mind right off the top:
Fort Wilderness has lots of neat stuff like hay rides, campfires, pony rides, canoe trail, etc.
Port Orleans has a carriage ride.
Lots of resorts have boat rentals.
Get a hair cut on Main Street.
Visit the stables of the Main Street horses at Fort Wilderness.
Ride in the front on the monorail and take in the sights!
We are doing the Pirate and Pals cruise on our next trip. It has a Captain Hook, Smee, and Peter Pan meet and greet and a fireworks cruise.
We did a free photo shoot of my DD in her princess dress at Exposition Hall on Main Street (had it put on the PP card).
We had a caricature drawn of my DD at our hotel and had it framed. We love it. He drew her as a mermaid and I had it framed with the picture of DD meeting Ariel.
Some hotels also do hair braiding and tattoes.
You can also get a very nice face painting at AK.
Stop and watch one of the street shows in World Showcase in Epcot. We did a few and found them to be very good.
Do the make your own candy thing at Goofy's in DTD.
Do the new hot air balloon thing in DTD.
Make some pressed pennies.
Do a private tour or swim with the dolphins at Epcot. I've heard lots of good stuff about the Segway tour there.
Do a passport book as you tour the countries in Epcot.
Wake up Tinkerbell at MK in the Tink's Treasure store.
Walk down the boardwalk at night.
Do the Wonderland Tea Party at the Grand Floridian.
Go check out some of the really nice/unique resorts like Beach Club or AKL.
Visit one of the mini golf places.
The best thing we did on our trip was a private photo session at the GF. I got some wonderful family photos with the most awesome backgrounds imaginable! Many other resorts are doing this now too.
Here is a link that has a long list of "overlooked things to do" at WDW:
http://allears.net/tp/ola.htm
Hope this helps a little.