These two videos are so far the only ones, that I've seen, that have summed up the plot or the basis of one of the characters in Elfen Lied. The first was actually the one that sparked my interest in the series in the first place.

Weight of the World - Saliva http://www.youtube.com/watch?v=ZGvSuqkF-vI

Rewind - Pillar http://www.youtube.com/watch?v=nkFgSqSp2eI

Post your Elfen Lied related videos here if you want; prove me wrong that there are better videos out there.