NEOLiNES

Link Spotify tracks to your posts and pages using uri-based shortcodes.
Ex. 
[spotify:track:2lBpN5CZ3zLyVIPejUhN6Y]
Attention! 
At this moment you can NOT link albums, playlists or artists, just tracks.

WP-Spotify

Link Spotify tracks to your posts and pages. Including widget.

stesvis

Allows you to add a playlist to pages, posts and sidebar. Just create your playlist and paste the shortcode [mp3playlist] where you want to draw it. To add multiple playlists please upgrade to the <a href="http://wordpress.phpanswer.com/playlist/" rel="nofollow ugc">FULL version</a>.

MP3 Playlist Lite

Short description Allows you to add a playlist of MP3 files to pages, posts and sidebar.

WP-Spotify vs MP3 Playlist Lite