Most people use Alfresco via their native file manager (Windows Explorer, Finder, Nautilus...) thanks to Alfresco's shared drive interface.
A shared drive is convenient, but what happens when your network connection disappears? The shared drive disappears. It is how shared drives are designed to work. No network, no shared drive.
What if you are in the plane, in an underground data center, or in the subway with no reliable network access?
One option is to checkout files you want to edit offline, but that is not a satisfying solution (duplication, out-of-date versions).
In those cases, you will need to use a synchronization client.
Hopefully, Alfresco offers interfaces for many protocols, so you have different options to choose from.
1) CmisSyncVery similar to the Dropbox client, lets you sync with any Alfresco content.
Free, Open Source.
.NET/Mono, Linux/Mac port not finished yet.
Not to be confused with an older project that has the same name and comes up first on Google, hosted on addons.alfresco.com and SourceForge.
3) FTPboxIf you like DropBox, you will love FTPbox.
The user interface is the same, with tray icon and almost no configuration needed.
Forget about 2GB limits and the security risk associated with externally-hosted data: you now have an unlimited DropBox for free, and the files are straight from your smart Alfresco repository!
The bad news: FTPbox is not compatible with Mac/Linux.
The good news: FTPbox is open source, so porting to Mac/Linux is a matter of motivation.
4) OFSUNIX users will know that FUSE allows to easily mount/unmount any kind of filesystem.
OFS (Offline FileSystem) allows you to maintain an offline copy of any remote filesystem.
It can take advantage of Alfresco's NFS interface.
Unfortunately, this solution is not usable on Windows until Windows allows userspace filesystems.
5) WebDAV SyncWebDAV Sync is a command-line tool that can synchronize documents using Alfresco's WebDAV interface.
Programmers love command-line tools, but it is not for office users...
WebDAV Sync is portable (Java) and open source, so it is a great choice for integration with existing client-side software (for instance if your company has a custom VoIP/chat/PIM app)
ConclusionI was hoping that version 3 of Adobe Drive (which supports CMIS) would offer an option to cache documents for offline use, but unfortunately it does not.
For now, CmisSync and Alfresco Desktop Sync are by far the most usable.