One of my articles in my website rank for number 1 in Google for one longtail search phrase. Adwords Keyword tool tells me this search phrase gets 1K searches per month [exact match]. While looking back few months of traffic and keywords bringing in that traffic (Google Analytics), I agree with the Keyword Tool: I get almost exatly 1000 unique visitors throgh Google for that article by people searching that term. So it seems that KW tool is quite accurate actually ??