PC based oscilloscope and spectrum analyzer

Here I am going to put some of the cool ideas of making a PC based Oscilloscope.

cool one I found here is
http://www.geocities.com/lptscope/

http://www.nbb.cornell.edu/neurobio/land/PROJECTS/TVnuS/index.html
http://www.nbb.cornell.edu/neurobio/land/PROJECTS/VideoScope/