there kinda walking the fine line with the spyware ,browser hijackers ,and stuff along that line.
some of it is legal (just barly) and the rest is malicious code (which is illeagle)
if you find a site that has that stuff scripted you need to turn them in either to your AV or isp ...
the last 3 pc's ive seen infected caught it while browsing Wallpaper sites (and no not those type of sites) and one from a shopping site i believe . (hard to tell it had way to many cookies from all over on it)
the one that tried to get me had 7 different Trojans/worms running from it . these sites are defentally illeagle and should be fined/banned for doing this.(yes i ratted on it )