Dropbox is an easy to use freemium cloud storage solution. It has a client sync utility for multiple platforms.

Nomadesk is a leading provider of file sharing, storage and synchronization software.

AkrutoSync helps you automatically sync Outlook across all devices.

Resilient, fast and scalable file sync software for enterprises and individuals.

Memotoo sync all your contacts from Gmail, Facebook, phone, Thunderbird, Outlook, etc in a single address book.

Eversync is an online bookmark sync tool.