I saw a guy in Kittyhawk, NC fly a stack of kites so large he had to harness himself to the bumper of his car. At points his feet would lift off the ground and he was suppported in tension between the kites and the harness. Needless to say, he was in some serious good shape.

I've got a stunt kite (your basic single delta), and it is a lot of fun.

-Zeke