One of the best features of the new Amazon MP3 store is the new album music preview. Single click to preview all the tracks, all Ajax loading in the page. 30 second snippets from each track automatically play, cleverly from the middle of the track, not the start. Simple and effective.
Thanks to last.fm I've learned I need some Air in my life, but their albums vary quite a bit. The previews are great; I'm finding I like the older stuff like Moon Safari and Primiers Symptômes best.