Baikal is pretty nice as a cal-dav/card-dav server with a UI. I can sync it with gnome evolution, thunderbird, an iphone, and android (but required an app). I

Baikal is pretty nice as a cal-dav/card-dav server with a UI. I can sync it with gnome evolution, thunderbird, an iphone, and android (but required an app). I haven’t tried it yet, but I’m curious about caldavzap. A web calendar UI that syncs with caldav. There’s a neat tool called vdirsyncer that keeps a local offline copy of your contacts/calendars that works with it as well.