I have a computer business and considered doing this. It seems to make sense in your situation, however in mine I am concerned about security. I know I have the capability to show a public Google calendar without showing appointment information, however even Google themselves also warn about the security implications of making calendars public, so I've been very apprehensive with doing this. My initial thought was that doing so would make my online appointment scheduling easier, however, I rethought it and also decided that I didn't want customers to see all of my potentially-available time (I like to have weekends off for example, etc). So, I've stuck with my old-fashioned way of doing it and responding to form emails with possible appointment times.