Check out this first person footage of a ride on this "single-pipe alpine coaster" in Mieders, Austria:
Damn that is wicked, imagine if this was your backyard and you could go on it any time! Here's another view of the ride:
The guy who took these shots says it was around $10 per ride, that's well worth it if it's as fun as it looks - hell I'd pay $50+ as long as there was a guarantee I didn't get stuck behind someone slow. We need these things in the states!
Update: It turns out these things do exist here in the U.S., check out this clip of one in Park City, Utah. Like the one in Austria it appears to follow a ski lift route. This one looks a little safer.