File Sync and offline access

I'm expanding my list of original contenders to include online backup services:

ReadyNAS Remote - http://readynas.com/remote
- Free (with purchase of a ReadyNAS)
- Network share access of ReadyNAS from anywhere.
- No offline access
- No mobile app
- No caching, poor performance
- No automatic backup or syncronization
- Sharing is difficult or impossible (at the user/share level, depends on ReadyNAS Configuration)
- Remote access from guest machine requires software installation

Dropbox - https://www.dropbox.com
- Agent runs against folder(s) on your PC
- syncing differences/changes to the cloud when necessary.
- offline changes are synced when online again.
- Local disk must contain full set of files.
- Web access (incl. gallery)
- Sharing
- iPhone app for documents/photos
- 50gb storage is $9/mo

ZumoDrive - http://www.ZumoDrive.com
- Agent runs on each PC
- ZumoDrive appears as a mapped drive letter
- ZumoDrive uses HDD space as configurable offline inteligent cache
- Syncs Folders too
- Intelligent Support for iTunes, iPhoto/Picasa, etc.
- Web access to all files
- Sharing
- iPhone app for music, photos
- 10, 25, 50gb for $3, $7, $10

Mozy - http://www.mozy.com
- Online cloud backup, single machine, single user
- Web and virtual drive access
- unlimited space for $54/year

Carbonite - http://www.carbonite.com
- Competes with Mozy
- unlimited storage for $54/year

Windows Live Mesh/Sync - http://www.mesh.com
- Agent runs on each PC
- Syncs folders to cloud
- Browser access
- No intelligent music/photo support
- No iPhone app
- Free. No word on available space

JungleDisk - http://www.jungledisk.com
- $2/mo for backups
- or $3/mo for virtual drive and multi computer sync
- includes 5gb, additional space billed by Amazon S3 ($0.15/gb/mo)
- web access
- portable USB version
- data de-duplication
- can backup network and portable drives