An allowlist for ad servers that aren't obnoxious.
As someone who runs a few sites that are dependant of Ad revenue, I understand the need to run ads. There are some companies who are good about making non-obnoxious ads (Google, for example) and other sites that have an ad system internally (Amazon, for example). I'm ok with ads, as long as they aren't blocking views, in your face, promotinng bad science, crap sites, etc. This is a list of those sites.