If you've ever needed to convert audio files between formats without losing their metadata, you'll appreciate sneetchalizer, a Ruby script that wraps standard audio conversion tools and metadata libraries. It's easy to use, well documented and helpfully verbose while running.

For example, to convert a folder of FLAC files to MP3 using LAME's voice preset:

sneetchalizer --in=flac --out=mp3 --out-optionhook="--preset voice" --out-directory=./output --rename="%t_voice" --threads 2 ./input