Do you know what passes for an acceptable click-through rate on online display adverts these days? 0.2%. That means that, for every person who clicks on an ad, 499 other people either a) complete overlook it b) see it but do absolutely nothing with it or c) print it off, then burn it in some sort of furious pagan ritual.
Everyone knows the holy grail is peer-to-peer recommendation, or "earned media" - and that's the saviour of online display, too. Instead of clogging up your site with perennially unclicked litter (or paying to clog up someone else's), why not combine brand and site to stage a Co-buy which, by its very nature, rewards and engages the audience?
Use that inventory to kickstart the Co-buy campaign, with a message that inspires key movers to share the promotion with their friends, then sit back and watch as that solitary advert is converted into hundreds of thousands of impressions on Twitter and endless appearances on people's Facebook news feeds.
There's still huge value to be had from online display advertising. But "sell, sell, sell" just isn't selling anymore.