What are soundfonts?

These are collections of WAV files with optional instructions, such as looping (sustain), oscilation (vibrato), and combinations (kits).

Can soundfonts create authentic SNES sound?

The instruments themselves are "authentic" sounds, but re-creating the DSP (reverb/echo) is what makes it sound truly authentic. Some games use heavier DSP than others, like Secret of Mana.

Cool, so how do I use them?

In order to use these, you'll need a Digital Audio Workstation (DAW) such as Fruity Loops, or LMMS.

What about commercial use?

In the US, you may have fair use protection, depending on the nature of the project, and how much the sound is altered. Consult an attorney before selling anything that uses these samples.