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. :-(
Similar to CloudFlare but more expensive ($30/mth no ssl, $130/mth with ssl) it accelerates web sites through the use of CDN, js/css combining, etc.