In a similar vein to cloudflare / yottaa, strangeloop offer a performance enhancement service through a physical / cloud based appliance. It uses the standard techniques, js/css combining, sprites, cdn, tailoring to the browser, and so on. No pricing. :-(
loudFlare is an automated CDN / content acceleration type service. It acts as a reverse proxy providing some sort of heuristic security scanning, logging of traffic, and an automatically configured CDN. $15 + $5/site/month.