…or at least some form of automatically preventing advertisements in my archive of websites
Two methods that I’ve had success with (thanks to guidance from sjk):
Get the AdSubtract.css, store it somewhere and set Preferences > Web > Stylesheet to point to the place where you stored the style sheet. This works well, but AdSubtract has not been updated for a year. It is being ported to GlimmerBlocker.
So, the second method I’ve used successfully is GlimmerBlocker. It’s one of the few hacks that hasn’t misbehaved on my machine.