Vitamin has a good article about how to optimize your Javascript for speed and efficiency, as old techniques won't fly in a "Web 2.0" world. Cal Henderson's best practices include compression, caching, and letting PHP or other server-side technologies do some of the work.
The article is sort of long, but it's a good read, complete with code examples so you can actually see what he's talking about. There is also a good discussion going on in the comments, with people questioning some of the techniques and adding their own.
1. Web 2.0 is a lie. How can something get a version number which evolves itself and is not produced like a program?
Posted at 6:27AM on May 26th 2006 by MJ