I understand that we can block specific hosts and also content to lessen the possibility of downloading bogus files. These methods however are not without drawbacks (i.e. dynamic IP for host blocking and actually filtering out content you may be searching for - .jpg or .wmv files).

I know this is geting into the dodgy area of censorship, however, given the vast amount of traffic containing this "spam", would it be possible for the network to identify files that are clearly adverts and flag them?

That way, an option could be included in "filters" to say "Don't download obvious annoying adverts" (maybe not in those exact words!).