[digisth]

A great library for structuring your callbacks is "async":

https://github.com/caolan/async

I've only used it with node.js, but it's supposed to work in web browsers as well.

It allows you to think a little more procedurally ("waterfall" is especially handy here) while writing CPS code. Very good.

[Jare]

I have used it in browser games to load assets (images, sounds, data files) before starting a new state (menus, gameplay, etc). It's a fantastic library.

[rbrcurtis]

That's my favorite library! I think people who write in node must just see threads like this and laugh.