Seems like there might be a chance that FFmpeg will support the proprietary FLV Nellymoser codec within the month.

For those of you that don't know. Nellymoser is the codec used by the flashplayer and FMS to record audio from a users' microphone. Up until now the only place where you could ever replay these streams were in the flashplayer itself, locking you into the adobe jail.

• Nellymoser codec on Google Code
• Thread on ffmpeg-user