Convert NSF Files to MP3s
indecks writes "This tutorial shows an easy way to convert NSF (NES Sound Format) files to mp3s so they can be played in normal media players, or even used as ringtones. Now I have the Super Mario Bros '1Up' sound for my text message notification, and I have Mega Man 3's 'Snakeman' stage music as my ringer. Sah-weet!" (The method demonstrated does require Windows, note.)
... just use Winamp and get the .NSF plug in. Or any input plugin for any exotic format that you enjoy. And switch to the disk-writer output plugin. It's rather beautiful and has worked for, what, like 8 years now?
More Twoson than Cupertino
With Linux (or almost any other unix-like OS), you can just record off the sound card using ALSA-based tools.
Either an emulator while recording from the audio mixer, or nosefart (nsf winamp plugin) and diskwriter as output.
Then I trimmed the sounds and used lame in high quality mode to compress to mp3 format.
For a slightly more obscure video game ringtone, you can use VGM2MIDI to turn your Sega Master System VGM music file into a perfectly useable MIDI ringtone. The FM processor in the Japanese version of the SMS made for much better music than the square and triangle waves the NES was capable of, and as a result the games have much better soundtracks for listening to.
I've got the Phantasy Star theme going right now, and it's better than most NES theme songs. Mario and Zelda are too pop culture, and just about anything else isn't worth the effort.