a little batch script that create an m3u playlist for each sub-directory of the given base directory that contains mp3 files, and an m3u playlist containg all the child directories in the parent directory if the tree structure actually goes that deep

mp3playlist_creator.sh

#!/bin/bash

BASEDIR=$1
if [ "$BASEDIR" == "" ]; then
      echo You must specify a base directory
      exit 1
fi

cd $BASEDIR
BASEDIR=`pwd`

# Remove existing playlists
find . -name '*.m3u'|sed -e "s/^/\"/"|sed -e "s/$/\"/"|xargs rm -f

# Remove funky Mandrake backup files
# find . -name '*~'|sed -e "s/^/\"/"|sed -e "s/$/\"/"|xargs rm -f

find . -type d |sort| while read -r DIR; do
      cd "$BASEDIR/$DIR"
      find . -type f |grep -v m3u | grep -i mp3 |sort> '00-Playlist.m3u'
done

Replacing '00-Playlist.m3u' with "$DIR".m3u would create the play list name using its directory name.