I found a free Windows program to find and listen online music for free, it's Freemake Music Box.

It does just a simple task: search your song online (eg: YouTube/ftp, etc...), but it does it terribly well, the interface is clean and simple, without banner or adware (Almost impossible, I'll say: how they could monetize? With donations).

Finally QQ Yinyue found a challenger! (it's a chinese software that essentially does the same thing)

The only weak point that I found it's that you can't download songs, just listen. Will this functionality be added in a next version? Or it has been intentionally omitted for copyright reasons? We will see...