I've been into slacklining since I saw the ISPO 2009 video and decided that it was something I wanted to participate in.
If you've never heard of it, a slackline is a thin piece of webbing tied between two anchors for funambulism. The line isn't actually slack like a slack wire, but I guess it gets its name from the dipping when stood upon - very unlike a tight wire. The flexibility of most lines give them a trampoline-like quality, but they also have the unique challenges of rapid sideways swinging (unlike the controlled side to side of a slack wire) and line torsion (the tendency for the line to twist on itself under pressure). Invented by bored rock climbers years ago, it's evolved into a conduit for rad tricks, but has yet to be embraced as a performance apparatus. Probably because it's really, really hard.
That's why people like Cihan Calis blow my mind. While I'm struggling to walk on the damn thing, he's BREAKING on it. With one hand down, he manages loads of bboy inspired threads and footwork - a completely unique style in any equilibristic art. Not to mention landing a back flips back on the line.
Obviously it's not a live performance but a collection of hit tricks and combos. I don't think I've ever seen anyone actually perform on a slackline. You're dealing with a lot of variables that I guess are easier to control on other types of wire, so although you might be able to hit a trick one time it's not easy to make it consistent enough to perform it with any kind of regularity. Who knows, though, I could be wrong. If Li Wei can swing on a slack wire in a one arm handstand then I reckon anything is possible.
Cihan is using a Gibbon Jibline, a completely affordable and incredibly easy setup that I would recommend to anyone trying to get into this.
For more Cihan, see his YouTube page here.