It's taken a while, but 2K Sports has released a demo version of Xbox 360 snowboarder Amped 3, which you can download now from Marketplace.
The 767.03MB demo (yes we counted) seems to consist of the Lower Resort area of the Northstar mountain, which basically means you've got quite a large stretch of mountain to explore and play around with, and a number of the game's early challenges to try and play out, from the novel (collect Easter Eggs) to the more traditional points-based stuff. There are also lots of people to impress when you fill up your special "I'm hot y'all" meter.
The game's pretty heavy on the Jackass-without-irony stuff, but don't let the presentation put you off - Amped 3's by no means awful, even if it does wind up being a bit easy in the long run. Give it a go and see what you think.