"It seems like this should be pretty easy, and indeed Google does provide tools to calculate ROI, but apparently not to optimize it. What they do provide is a t

"It seems like this should be pretty easy, and indeed Google does provide tools to calculate ROI, but apparently not to optimize it. What they do provide is a tool to optimize your cost-per-action. Does anyone know why this is?" I think you're wrong. Google does not and cannot optimize your cost-per-action -- you need to figure your CPA out because that is dependent on your business execution and flow. How can Google optmize your CPA if they don't even know your operational costs? With google's conversion optimizer, you are optimizing your ROI if you find the right CPA figure for each ad. IMO they did a great job with the conversion optimizer, by turning the complex problem of adwords ROI optimization into a much simpler problem of calculating your CPA.