I've seen today few websites which have a top spots in google/yahoo and when you enter this websites you're redirected straight to affiliate program
BUT when i looked at cache i saw whole page with keywords etc
so looks like someone is doing nasty trick, send google/yahoo robots to proper page with SEO etc (to get top spots in search) but redirecting all humans to affiliate programs
question is: how ? hmm maybe simple trick in htaccess, when referer use firefox/chrome/ie then redirect
so bots would hit proper page to cache it and put in rankings but humans would be moved straight to affiliate program..