http://www.radio.imradioha.org/PC_Based_Test_Gear.htmTo the best of my knowledge at the time of the creation of this page all of the links are to freeware or free for non-commercial use sites
The PC Sound Card as a Signal Generator or Oscillator:
PC Based Oscilloscopes:
PC Based Test Meters:
Spectrum Analyzers for the PC:
Multi functional ++:
Multiple Offerings:
Other: