Like http://www.ratemds.com ?
or MyDocHub.com or revolutionhealth.com

I haven't used any of them but I look forward to doing so.
The University of Washington came up with a diagnostic program based
on answers that the pateint gave in a branching patient intake
questionnaire that was over 90% accurate on followup. Thing was that
there were a few excess false positives over the live doctors, but
about 20% less false negatives than live physicians.
That is possibly because the psychologists or health information
specialists that constructed the questionnaire at UW were doing
studies on the best questions to ask to get the right data for
diagnosis.  That was a number of years ago. I always wondered what
happened to that diagnostic questionnaire system, since it seems like
now the patient could fill out the form online while at home the
results could be sent to the doctor to aid with his diagnosis.
Physicians are just like everyone else, when they are tired, sick,
worrying about taxes or children or divorce they can be distracted.
When people are tired they revert to the familiar. Systems like the
one from UW help keep docs aware of possibilities other than those
they are most familiar with.