I'm a big fan of Rachel of the original San Francisco Compact (the buy nothing new group), and not only because she is the only person I've ever known who has given, as a Christmas gift, the promise to pick up a certain number of piles of other people's dog poop.
To contextualize, Rachel walks dogs, and I think she gave the gift to a client. In that same year, she asked, as a present from her dad, that he clean all the junk out of the trunk of his car to make it more gas efficient. That Christmas for Rachel was about giving and receiving gifts of sustainability. Really creative. Read more about it here.
Over on Sustainablog, Elizabeth Redmond writes that, after her family made gifts for a couple of years and then pooled funds to buy only one big gift for each member of the family for a couple more, they have decided to give donations to microfinancing charities:
Microfinance creates social lending networks that gives us lenders the opportunity to connect directly with borrowers who normally wouldn’t get the support of a bank. This allows people in poor countries and rural areas who don’t have access to traditional banks or don’t have the credentials necessary for a bank loan, to start a business. (Check out Elizabeth's favorite places to give here).
As for me, and I've written about this in more detail, I like the idea of giving shared experiences--couples massage, theater tickets, live music tickets, for example. This works for me because it has the benefit of giving the people on my list who don't want my wacko environmentalism shoved down their throats something they want without littering the world with more stuff. And it has the benefit of bringing people together, too.