You might want to consider Terrasonde's Audio Toolbox. It's not software, but a hardware product. I don't have first hand experience, but it appears to do everything you want and much, much more. It features a display screen, signal generator(s) and has a built in microphone. The website is www.terrasonde.com
Frequency Spectrum Analyzer Software
I believe I've read about a few software packages for frequency spectrum analysis. I'm interested in this to tune the room as best as possible and to equalize the bass (not something I really want to do, but I think it is necessary). Although I can use a pressure meter and one of the stereophile CD's, I would prefer a spectrum analyzer that looks at all frequencies at once (for wave addition or nulls). What software is out there? Has anyone used it and with what results? Where can it be purchased? How important is a good quality microphone with this type of software? Also, my room is not rectangular so the programs that evaluate wave addition and nulls will not work for me.