I use Google's Pagespeed Service, which is free and in beta. They say they may charge some day. But the support... I have "proxy errors" reported, which would appear to be an error on their end. Contacted support via email and was told to expect a response within 3 business days. So that was Thursday morning, it'll be at least 96 hours before I get a reply. Maybe up to 120 hours. Glad I moved the site instead of waiting.