Processing is a great open source application for artists and experimenters. This Minority Report style application was created in 20 minutes! Amazing! Check out the link to download the source code. [Thanks Guru]
Today I read about touchless an opensource sdk microsoft has released. it enables you to track objects using a simple webcam to create apps similar to a multitouch display.
Then I spent about 20 minutes coding a processing sketch that does roughly the same :-)
As you can see in the screenshot I cant affort the same cool toys the microsoft coder has in the demo video, so I had to use some post-its instead
Read more about “Touchless” Multitouch in Processing