I recently found a couple of programs that I think are nifty for hobbyist electronic testing use.
The first one is called Visual Analyser. It does everything from voltmeter to LCR. Just The website also a a couple of schematics for building the probes. The software is free to use and can run on Win9x to Win8.
The second program is called ScopeOnPC. This is another simple PC oscilloscope. Instead of using a soundcard it uses the Parallel port on the PC. Uses a simple ADC converter built from a ADC0820 or a TLC0820 with some 74 logic love. The software has a DOS version and Windows version.