Futures in JavaScript

This was a useful article to read:

http://www.xanthir.com/b4PY0

It explains what futures are (a relatively new feature in JavaScript, from last year) and how to use them.  This is useful when managing ajax-heavy applications when you have to deal with errors, chaining, combining, waiting, and ordering of ajax calls--among other things.

MSDN also has a good article on futures:
http://msdn.microsoft.com/en-us/magazine/gg723713.aspx