Ask HN: looking for ifttt for Amazon monitoring

I'm looking for a service which polls my server to say "If my home webserver is not responding, start a new AWS instance to replace it" While I theoretically could do this with a $15/month micro instance, that is both: more than I want to spend on this service, and not the best choice given if my web server failed my monitoring instance may have also failed. What do other people use?