I had the idea to analyze a live sound input in the fashion of an oscilloscope, and rather than actually buying a real one, I was wondering if there were any programs out there that are available; possibly free ones.
Here’s another one http://xoscope.sourceforge.net/
Note also that it is wise to buffer the input in some way to avoid blowing up up your sound card.
See http://www.hitsquad.com/smm/cat/OSCILLOSCOPES/ [hitsquad = free- and shareware search engine, no commercial link]
Note that the main reason why soundcard-oscilloscope software today is not developed anymore is that with standard 16-bit soundcards the sample frequency is too low and the s/n-ratio too bad for real good analysis - but it’s still lots of fun.