[Plugin: Audio Player] use in widgets without any extra plugin

You can make work the shortcode [audio] in a widget adding a line of code in audio-player.php

You only need to add this line into function AudioPlayer()
add_filter("widget_text", array(&$this, "processContent"));

for example, I added it in line 161 before the “}”

http://wordpress.org/extend/plugins/audio-player/