VISUAL ANALYSER 2011 soft scope (beta version) consists of the scope, spectrum analyser and multifunction wave generator.
On my opinion it's the best today's program for the amateur guitar-related electronics.
In spite of couple negligible bugs the program is great (!).
IMPORTANT: VISUAL ANALYSER 2011 has the very special D/A function (D/A field in the Scope mode). This function allows this scope to observe sine-way signal up to 15-20 kHs (!) without any noticeable distortion while other (simple) soft scopes can hardly do it with the 3-5 kHz sine-wave. All you need is to have simpliest 44 kHz/16 bit sound card and to engage the said above D/A function.
Download files and discussion is here:
http://casa.accattatis.org:9090/forum.ghp
Thanks! I'll give it a try...
These are also nice ones...
http://www.zeitnitz.de/Christian/scope_en (http://www.zeitnitz.de/Christian/scope_en)
or
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=18254 (http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=18254)
I'm sure there are more, just google "soundcard scope"...
Greeties,
Wim