Synchronization Service
fruux is compatible with CalDAV and CardDAV.
Free sign-up
Google Calendar is CalDAV Enabled.
CalDAV/CardDAV service
Landmarks is a CalDAV/CardDAV service available initially in Germany.
Synchronization Service
Memotoo is compatible with CalDAV and CardDAV.
Sign-up required
MobileMe Calendar is CalDAV Enabled.
E-Mail/CalDAV/CardDAV service
servermx.com offers e-mail hosting plus Contacts and Calendars via CalDAV and CardDAV support.
Free sign-up
The new Yahoo! Calendar is CalDAV enabled.