For those unfamiliar, GNUCITIZEN is quite possibly the best site on the internet for web security research that is not affiliated with a vendor. pdp has covered topics such as backdooring Quicktime files, building XSS attack libraries, improving existing protscanners and history stealers, and even a JavaScript web crawler (which is currently receiving a massive improvement...). Much of his work ends up appearing in live attacks a few months after the info is released.
Needless to say I was really happy when pdp asked me to write a blog entry for his site. I wrote up a meaty overview of the different methods JavaScript can use to send HTTP requests, as well as the pros and cons of each.
