I discovered this sport a few weeks ago through the movie 'highliner' (with dean potter) and i'm totally fascinated..i also think that it is a very good balance training for rails and big air jumps...
[img src="http://www.bernies-bergwelt.com/slackline/nov2005/DSC03092.JPG"]
[img src="http://www.snoo.at/slack-line/forums/get-attachment.asp?action=view&attachmentid=194"]
also, check out this pic (One of the most impressive pics EVER! THIS GUY WALKS THERE WITH NO SECURITY_ ROPE!!)
www.filmfest-stanton.at/04/presse/highliner.jpg