There are a lot of bands doing this these days and making money. Reggae, bluegrass, jazz covers of famous songs. There is even a band called Rockabye Baby who have released a string of albums featuring covers of various well-known bands in the style of lullaby music. The only track I've heard is Alec Eiffel (thanks to the frankblack.net!) by the Pixies and it was pretty good, just imagine all those middle aged Pixies fans with babies who might like to buy this for them. It is both a winning marketing gimmick and a neat idea into the bargain. So if you have a good idea and you can play all you need to do is record some songs and punt it out on the internet.