Are you worried Google will learn your company's secrets? Some companies warn their employees not to use the new Google Drive or Gmail for these and other reasons.
Device Index SugarSync
Microsoft SkyDrive cloud storage service gets competitive with Dropbox and SugarSync.
Apple's iCloud service isn't fully baked yet for mobile document access. Dropbox and SugarSync are better suited for this task and combined give you a total of 7GB of free cloud storage.