NoScript. Whitelist.

Glimmerblocker is great, saves looking for extensions and covers any browser (it's an http proxy, and has auto filter lists for extra goodness).

Well, if you add up all the Middle East imports on the list for 2007 (Saudi Arabi, Iraq and Kuwait), you get ~24%. So I think it's fair to say most of it comes from somewhere else, if not just Canada and Mexico (those are the 2 biggest of the others though).