Dougal Campbell's geek ramblings

A friend of mine is looking for a web-based events calendar. He’s got a pretty big list of needs and wants, but here are some of the main ones:

• Ability to integrate into existing web site (look & feel, events lists on various pages, maybe unified logins, too).
• Single events, recurring events and floating events (same weekend each year type) plus multiple categories
• Separate yearly, monthly, biweekly, weekly, and daily calendar views for each calendar
• Unlimited web calendars on web site for different departments, communities, geographic region, etc.
• Downloadable calendar data available, methods to include: Outlook, PDA, iCal and vCal
• Create RSS feeds of upcoming events

I’m afraid that my calendar-fu is pretty weak right now, so I don’t have any recommendations for him. The server will have PHP and MySQL, of course, but another request was for a system that could work with other databases, or even flat files. Anything based around something like ADOdb or PEAR::DB would probably fit that requirement.

The last time I tried to find a PHP calendar app, the one I looked at was pretty primitive. Surely there’s got to be a decent calendar framework out there by now. So, any recommendations? He’s willing to consider reasonably-priced commercial offerings, by the way.