This isn't in support of Chrome or to down FF at all, but for ad blocking I've always just blocked ad networks' DNS addresses from resolving. Just point my router to a vps running DNSmasq and pull down the latest entries from easylist every week and bam - global ad blocking on your network. It has the advantage of allowing blocking on all browsers/systems. Good if you have non-technical peeps using your network too, as it'll save bandwidth and deliver nicer looking pages.