Ask HN: Anyone building (or have) a calendar suggestion tool?

I schedule a ton of meetings and go through the same headache all the time:

1. Send email "what dates work for you?" 2. Reply email "how about these dates?" 3. Reply email "can do that date, not that time" 4. Reply email "where do you want to meet?" .. etc.

I would love an app that allows me to send ALL the available times on my calendar through a simple email (just shows openings, not my calendar). The recipient can then click on an available time that suits their calendar and send me back a calendar file. Even better, they could sync their openings with mine upon reciept of a special mail type.

I'm well aware that you can expose your calendar and such with google calendar, but this is a simple solution that would essentially work with all calendars.

Any ideas? If that app exists, please let me know because I'd like to use it.