Regarding emusic. I have been using them for five years now (as a customer not as an affiliate). It's a great service if you like the music they offer. There are some things that they have there which are otherwise OOP. That's how I got hooked up with them. I was looking for an album that was long out of print and I saw that they had it in digital format.
From a user standpoint, I'd say it's pretty great.
Actually, I'll give you an example of what will draw people to emusic (provided you have the right traffic). Take the band Felt. This is a cult band from the 80s with some really influential music. Their releases are all long OOP and you can see on gemm.com that their albums either in vinyl or CD format can run up to $50 (actually I notice that Absolute Classics is priced as high as $80.
Now some people are collectors and they will pay the price for the original vinyl. Others just want to hear the music. emusic has all of the Felt albums and at current download prices they are about $3.00 each.