I designed these icons for the Last.fm client for Linux to fit with the Ubuntu Lucid mono icons and one for the Elementary monochrome icon set.
Designed in Inkscape.
You'll have to copy them over the current last.fm icons. For the Elemenary one, copy user_black22.png to /usr/share/lastfm/icons.
For the Ubuntu Lucid monochrome icon, copy user_blue22.png to /usr/share/lastfm/icons.
Restart the Last.fm client and under Tools>Options>Account you can pick the icons. Black icon for the Elementary theme, blue icon for the Ubuntu Luicd theme.