Company calendar recommendations? [closed]

I'm looking for a company calendar solution, and maybe a company directory utility.

• We're a cross platform workplace (Windows, a couple of Linux variations, Mac). We need clients (or a quality web interface) available for each platform.
• External hosting (e.g. Google calendar), is not acceptable.
• Open to commercial solutions.
• A good quality web interface to our IMAP server would also be a plus.

Any recommendations?

Not sure if you are willing to look into a complete collaboration suite. But Zimbra has awesome calendaring and not to mention the great email web client/server. They have an open source version(FOSS) which is great for most needs and a paid/supported version (Network).

This may seem odd, but our University used to run MeetingMaker which ONLY does calendar-but it does it well and with simple hardware requirements. You can also purchase an add-on that will give you push calendar sync to smartphones. The pricing was not unreasonable for MeetingMaker.