Review updated 7/29/08
Even if you have only one computer, you might want to keep a synced copy of your important files online--and the easy-to-use SugarSync is a good tool for the job. If you ever need to work on another computer temporarily, you can access your stored files (download them, update them, and then upload) from any Web browser, without installing the service's software. SugarSync will update the matching files on your main machine the next time that PC is on. (See "Stay in Sync" for more on all of the sync services I tried.)
For more functionality (such as syncing multiple machines), you'll need to install the SugarSync Manager on each. You can use that utility for syncing chores, or just drag files to the Magic Briefcase folder that SugarSync adds to your Documents folder.
While the mobile version of SugarSync's site makes synced content
SugarSync lacks the remote-access desktop-control
SugarSync lets you e-mail
For users who want to store files online but not sync them to the originals, SugarSync offers some backup-specific features. Backups may be your only source for an older version of a file, since SugarSync lacks the versioning features of Dropbox and Syncplicity.
SugarSync may be a decent backup and sync tool for home users and photo enthusiasts. But its limited file-sharing and remote-access functions make it less desirable for business users who need to work collaboratively on multiple files.