I need a calendar that I can use to generate appointments, get users info, and ask them couple questions for a strategic session. Something like this: http://go.andrewargue.com/start/
I've been loving Calendly--It links to my Google calendar, which I live and die by!
There are solutions already out there like Google Calendar and Microsoft Outlook, but I think you're looking for an appointment scheduling application. I did a quick Google Search for "open source online scheduler" and found this among the search results:
It seems there's a lot of stuff already out there that you can use, you just need figure out what exactly would fit your business needs.