Ccmixter.org have a ton. Also soundcloud. Aside that the usual ways like Youtube.Also keep an eye for remix contests. Plenty of good vocals from a few well know projects/bands for free ,a chance to get featured and earn some $ or other prizes. Source: over 1 year ago

Find some fitting music to use in your videos. Source: almost 2 years ago

Creative commons remix community (some are non-commercial): ccmixter.org/. Source: about 2 years ago

For Free and non-copyrighted samples: CCmixter and Freesound. Lots of good stuff there. Source: about 2 years ago

Http://ccmixter.org/ tons of music with a variety of creative commons licenses. Source: about 3 years ago

I use binaural beats for types of programming work where it is useful (I've tried Brain.fm and focusatwill.com and prefer the latter). Source: almost 2 years ago

I take focalin in conjunction with listening to music at focusatwill.com. The music has surprisingly been very helpful for me. I used to try to listen to classical and every time there would be a pause between songs, my attention would be disrupted and I'd drift. I did buy the year-long subscription, I think it's around $50, but totally worth it if you can afford it. The music offered is specially engineered to... Source: over 2 years ago

A recent one for me has been Focus@Will. It’s meant that I can reduce the amount of decisions I have to make when it comes to getting on with anything that requires focus. I no longer dick around on Spotify trying to find the perfect focus music - I just press play and crack on as best I can. So far the music has been really good at getting me in the zone (it’s often just getting to the point where I’m ready to... Source: over 2 years ago

Cool stuff. I use brain.fm and focusatwill.com. Brain.fm is my favorite because it's generally higher quality and I managed to snag a life time sub a few years ago. Source: about 3 years ago