Blender Balloon Simulation
Alex Aylesbury responds to requests here on BlenderNation and explains how he created his floating balloons.
We posted a little example of Camera Tracking using Blender during the Summer on BlenderNation, and a couple of comments asked how we did the Balloon Simulation. It’s a quick and easy process, but when we did it we had to experiment a fiar bit to have a Rig hold and move the string. We’ve done a short video tutorial, and you can download the .blend file that we made in the tutorial.
We hope some of you find it of use.
Link

Blue red and yellow balloon floating in the air.