[limpangel]

I have been using Sync ever since it was introduced in FF(4 I think?!?) and I have to say it worked really well for me.

Not only does it sync your usual suspects bookmarks/passwords/history, but it also syncs your installed addons and their settings (if supported). For example it syncs AdBlockPlus's list of whitelisted websites.

Another neat Sync feature is the possibility of seeing the open tabs on all your synced devices. For example I am looking right now on my phone and I can see the add HN comment tab in the mobile version of FF (Android).

On top of that the Sync server is open source so basically you could deploy it yourself if you have privacy concerns, although your data is encrypted before it is uploaded to the server anyway.