You can’t use Rhapsody to provide free listens in-place in your own site anymore. Soon you won’t be able to use iMeem or iLike. Spotify has never done them. YouTube isn’t anywhere near comprehensive.
There are lots of vendors that will give you a free sample if you’re on their site. That’s what’s powering music on Google — they do a pop-up to the vendor’s site.
The only healthy vendor supporting embedded players is Lala, which has an embed in third party pages like a Rihanna review on Pitchfork.
Grooveshark lets you export songs/playlists as widgets. For free.
I don’t really agree that YouTube isn’t comprehensive – they have a huge catalog of slideshow/record spinning videos with pretty much all music ever, sans quality.
I see people using it in this way all the time in embeds – it’s the option with the least friction and least restrictions.
YouTube has a different catalog with some overlap. There’s lots of stuff that you’ll find on any mersh service that you won’t find on YouTube.
I didn’t find the original recording of “Way Out West” by Big Star just now, but I did find a live version from 2008. Spotify has the original but not the new one, YT vice versa.
It took a little doing to find a recognizable song that wasn’t in some slideshow/record spinning video, though.
Next epic smash up fight on YT is about publishing rights on cover songs. I don’t think the computer science will support auto-recognition.