It's pretty common to jam smaller ad units together -- e.g., put four small text ads in a 728x90 pixel leaderboard. But you're talking about something differen

It's pretty common to jam smaller ad units together -- e.g., put four small text ads in a 728x90 pixel leaderboard. But you're talking about something different. If I were an advertiser, I guess what I'd ask you is why I'd want dilute my message by sharing an ad with four others, when the cost barriers are so low for getting my message out on my own. How would I know all the traffic/interest would go to one of the other four? One common application for this kind of thing is something like click arbitrage -- go find a set of like offers which offer incentives for clicks, and try to drive traffic to them at a low cost.