SmoothSync
From dmfswiki
Just Sync is the name of a series of CalDAV-Sync and CardDAV-Sync spin-off sync apps.
Important note
Currently Yahoo's servers are broken (see [1] and [2] ). This issue seems to exist since Thursday or Friday. If you can not sync this is a Yahoo issue not an issue of this app!
These apps are designed and optimized for a specific service and use the well-proven sync engines of the generic CardDAV and CalDAV apps.
Currently the following versions are available:
More to come!