Program: resonic player
License: Resonic is free for personal use.
Description: "Resonic is a slick audio player and browser / directory player, built around a big waveform view.
Resonic plays your music files, sounds and samples out of your existing folders. It's built to be fast, reliable, and powerful. It does what it is supposed to do, without the bloat, and with exceptional usability."
Website: http://resonic.at/home | http://resonic.at/screens
Note: http://resonic.at/faq | http://resonic.at/download
Is Resonic portable?
Yes! Resonic was designed with full portability in mind.
Once installed in “portable mode†it can be run from all (write-enabled) portable devices like USB sticks / thumb drives without leaving data behind on the computer. In fact you can take your settings along with you as they are saved and restored per computer and user.
Looks interesting. I did not check the license, but it may be worth a look, once it comes out of alpha.