Have you always wanted to soar through the trees like, well, a gibbon?
There is a fantastic course just outside of Chiang Mai, Thailand where you can do just that: Flight of the Gibbon.
2015 update: I thought ziplining was just a warm country / warm weather activity. But I went up to Whistler, British Columbia in the first week of January and tried winter ziplining in the snow with Superfly Ziplines. Fantastic! Check them out next time you’re in Whistler.