Dessy is a DEsktop Search and SYnchronization framework for mobile devices. It allows file search using content, metadata, and custom tags, and synchronization of results, and entire file system subtrees.
mSync (Java) Use mSync to back up your files, contacts, and settings
GGSync A Java J2ME project for synchronizing Google gmail contacts with a cell phone. The synchronization is done directly using an existing internet connection on the mobile device. http://sourceforge.net/projects/ggsync/
Kepplr Kepplr is a cross platform Data Sync solution