One guy and an iPhone is all you need for some bomb ass musical creativity these days. The app used below is called Everday Looper and lets users record their voice or a beat and loop it back, and then record something new with the original recording now serving as the background. After a while, and if you know what you’re doing, you end up with a bona fide song on your hands.
The app is $5 and can be found on iTunes over here.
Further Reading: Using the iPhone to make melodic cover songs