I own a website called TubeShine, which is a YouTube playlist generator. Basically, it allows you to enter YouTube URL's, and then it henerates a playlist for you and puts them in a player which you can either utilize on your website, via a link -- or send to friends via email.
In the past the player didn't automatically move to the next video when the old one had finished, which was a bit beside the point of having a "playlist". But now I have figured out how to make it to that, and I have re-launched the website.
See the site at:
http://www.tubeshine.com PR:0

I have also opened a forum section for questions, comments and suggestions:
TubeShine Forum