Javascript: Some good links I found on javascript tips and performance

Was involved in the past few days on javascript performance optimization. Found some good links on the same.
http://aymanh.com/9-javascript-tips-you-may-not-know - Best thing I liked in this is some good explanation of null and undefined in javascript. Helped me understand an issue.

http://www.bloggingdeveloper.com/post/7-Easy-to-Apply-Tips-to-Improve-Your-Web-Site-Performance.aspx - This one talks about the loading images form multiple domains as one of the points - very interested and something which we are planning to implement