baabullah

This is a widget, you can put in the sidebar that display recent played tracks of an last.fm account.
You can set any last.fm username, limit the songs and refresh interval.
This plugin require jQuery on your template. If your template doesn’t support jQuery, this plugin will display your currently played song in image format.

LastFM Now Playing

A widget that display recent tracks of an last.fm account.

tpaksu

This plugin uses CSS technique to fix the png image transparency issue and jQuery to apply this script to all of png images shown in the page. 
This doesn’t work for positioned and tiled png background images. Maybe in next versions.

WP pngfix

Plugin that fixes the png image transparency issue on IE.

LastFM Now Playing vs WP pngfix