You know what I do? Whenever Quadrette and I are on airplanes, I pull out the SkyMall catalog (essentially just a catalog full of smaller catalogs) and we "window shop." I make mental notes of things that she reacts positively to and I put them on "my list." You could do the same - just sit down with a catalog one evening just for fun and look at items together - maybe you'll get some ideas.
BTW, this may help you in the future - I keep a list in my planner year-round, and whenever I hear her mention something she's interested in, I write it down. Any ideas that don't get used for Xmas can be used for birthday.
Some more ideas for you:
spa/salon treatment? (massage, manicure, facial)
weekend getaway vacation package?