My wife and I have a list (actually, she's reminding me of all the things we did prior and after I proposed to her in the MK rose garden - then we got married at the Pavilion). Here's the top 10;
1) If you have the extra funds, surprise your hubby and ask to reserve the Rose Garden in Magic Kingdom. They will supply you with bubbly (apple cider), personalized mickey champagne glasses, and a love seat to watch the fireworks. If it is a surprise - the CM can fake a great letter saying, "you have been randomly selected to receive a special viewing at the Magic Kingdom of the fireworks show". To this day my wife still can't believe she fell for that one. And, then I proposed with the castle behind me and the fireworks going. You could remind him how much you love him then... believe me, I made points for YEARS!
2) Take a walk to the dock after your dinner at V&A. Providing you're done before the fireworks go off, you can stand on the dock and watch them from the GF. It's a treat.
3) Sit on the beach at the Coronado and sit in a hammock together (there is also a hammock or two at the Poly). Make him read you a favorite note or email he sent you - or you could read one for him. I brought the first note I ever wrote my wife and read it to her. She cried, but she's an easy cry... but, I'm pretty sure it was romantic.
4) Buy a couple of Disney candles in the gift shop and turn off the TV & Lights in your room. Have dinner brought up. Even if you're staying at a resort with out room service, you can order delivery (call the front desk for details).
5) Make a smart-alec comment about an obnoxious parent... okay, not romantic, but your husband will thank you for it.
6) Dinner at the Contemporary's Cal Grill during the fireworks is a winner. Period.
7) Make a CD together at the end of your trip. On the last day, every year that we go to WDW for our anniversary (and on our Wedding trip) we make a CD at Magic Kingdom of our favorite things we did during our trip. They do not have all the music you will want, but it's still really neat to open a photo album and find a CD with musical memories on it.
8) Take a tour. Really. I thought it would be the LAMEST thing ever. I was so wrong. Now we do it all the time. My favorite (and what hooked me on doing the WDW tours) was the Segway tour at EPCOT. Tinkering around EPCOT on a Segway was beautiful. No crowds, the park is empty, and the sun is shining that early morning orange (make sure you try to go as early as possible). If your husband is a gadget fan... even better. There wasn't a frown in our group of 10.
9) Take another tour. The AK offers great tours. Do whichever one you want. But, it's a beautiful place to be in the morning with a limited amount of guests around you.
10) Call WDW-PLAY. They can give you some great ideas as well.
Best of all.... hug for 1 minute in each park.
. Also at Fort Wilderness, if you are both outdoorsy, I believe you can rent canoes or fishing boats. Maybe bicycle's too, not sure... Maybe a couple's massage at the Grand Floridian Spa? A stroll down the Boardwalk might be fun (I think that was mentioned already). Maybe a night at the Cirque du solei (i've never done that either)... Maybe a surprise in your room, like rose petals over the bed and candles lit (not sure if disney can do that type of thing). 
