Help/Advice needed in tracking visitors

Im using google analytics.. is a way to track the visitors, after they leave our site.. like where they are heading to after visiting our site?
either in Google Analytics or some other site which provides such facility or is there a blackhat method to do it?

I don't know of a BH method, but I know Webtrends will provide you that data

hey bro, thanks for the info..
but ti think their charge will be pretty high !!
is there any other advice/idea that you can give?