WhoSampled offers an extensive database of songs, samples, covers, remixes, artists, and more. According to its website, it's now tracking more than 1.2 million songs and nearly 622,000 samples. That data is powering Spotify's latest features, like its upcoming music discovery tool SongDNA.
Interesting. This will probably enable them to get significantly closer to their goal. I’ve tried their site a few times but it only had really mainstream, obvious samples. If Spotify can combine their song data with whatever system they have that isn’t just user-contributed, it’ll probably be significantly more useful.