Jukedeck lets you specify the kind of music you want and the length of track you need, and then it creates the music for you, which you can download for free. The entire process takes a minute or two.
You still have to request early access to be able to use the service, but I received mine pretty quickly.
I’ve embedded a short video about the service at the end of this post.
I’m adding it to The Best Places To Get Royalty-Free Music & Sound Effects.