What sites do you think are best suited to up and coming musicians?

Well Myspace is a must for musicians. You need somewhere to put up your songs and have all your information all laid out incase anyone wants to see it. I would also recommend Twitter, if you get to know the site well, and have it all figured out, it's great for promotion. You could have hundreds or thousands of people reading your tweets.

I know of a site that's out there that a musician can create a profile on, and put up songs for the public to listen to. The members can provide feedback to the musician, and the musician can even reach what this site calls a showcase and make enough to get a recording contract. I've listened to many artists there and have found some amazing undiscovered talent just sitting there waiting to be found. Message me and I'll give you even more details about it.

I don't know much, but if you have heard of the website slicethepie, it might be a good start. I don't know the policy so your friends might want to take a look at the faq.