'NoMoreDupes for Outlook' is an Outlook add in to clean your Outlook duplicates.
Sync2S3 synchronizes your files with the Amazon Simple Storage Service (S3), providing you with a secure and affordable backup solution.
Backup and restore your Outlook quick and easy. Your mails, appointments, journal, tasks, notes and contacts are saved. Furthermore your email accounts and other settings are included in the backup.
SynchPst - the easy way to synchronize data among two personal folders. Just choose either single or multiple folders/subfolders to synchronize. Synchronize all Outlook items including notes and distribution lists. Deletions are supported, too.