I don't want to rant about it but FLAC is totally overkill for most audio players and for most listening ears. I have good hearing according to medical examination, and a very nice hi-fi audio system (Rotel & Polk), and I find no way of distinguishing a high quality MP3 from a standard CD. The only exception where I noticed that FLAC files are really necessary is for ripping digital audio whose original is HDCD-encoded (which is non-compressible). Appart from that exception, there's no case for using FLAC as a playback format: use MP3 instead.
But don't get me wrong, there exists a valid reason for using FLAC: to allow for several re-encodings further down the road. It so happens that if an MP3 file gets re-encoded as an MP3 with a different quality, there will appear artifacts (defects). So I still believe that people posting FLAC files on the net are doing the right thing: they allow other people to choose which MP3 quality to use for storing those files. Hence, FLAC is a very good format for high-quality audio transmission over the net.
But since storing FLAC files for playback is mostly a waste of storage capacity, they need to be converted to MP3. Here's a quick way of converting a bunch of FLAC files into MP3 with minimum quality loss:
mkdir mp3
for x in */*.flac; do
dest="mp3/`basename \"$x\" .flac`.mp3"
flac -d --stdout "$x" | lame -q 0 -V0 --vbr-new --preset extreme -m s - "$dest"
id3cp -2 "$x" "$dest"
done