Good Into Javascript OOP Tutorial

I'm pretty good at procedural Javascript, but I'm a little behind on object oriented Javascript. Some of my more recent client side projects could have really benefited from some JS OOP knowledge, so I decided I better bone up a little bit.

Anyway, here is a link to an old, but still very relevant, OOP Javascript tutorial. There are two parts, just toggle the 1/1 in the URL to 2/1 when you are done with teh first part.

http://www.sitepoint.com/article/oriented-programming-1/1

[Update 1/22/08]

Here is a pretty good ebook on Javascript-

http://eloquentjavascript.net/contents.html