I've got to tell you guys about a demo done during a Fly In this summer I had never before seen anywhere, and I've been to a lot of Fly In's too !!
This guy was flying a high wing, don't even remember what it was, but probably an 80 to 90 WS and a really healthy motor

He tied a line that was probably about 150 to 200 feet long with a plastic pop bottle tied to the end with about a 1/4 of it filled with water. After he took off, the bottle eventually followed. When he flew in a tight circle, the bottle would eventually drop down like it was getting sucked down into a hole (just no forward airspeed). The neatest thing was when he had a 5 gallon bucket stuck out past the runway, started his circle, and eventually dropped the pop bottle into the bucket on the ground.
He put on about 15 minutes worth of cool stunts requiring some pretty nice flying

At Noon he did a tribute by flying the USA Flag from a long length. I've seen this before but it always it pretty cool I think. Had a release on the line so when he flew over and pulled the pin, the flag was caught and never touched the ground either going up of coming down[8D]
I've got video from a new camera, but can't figure out how to post it.