It's not often I have the urge or desire to blatantly plug a product, but in this case it's very well deserved. ExpanDrive, available for both Mac and Windows, allows a user to utilize remote filesystems over a variety of protocols.  It supports FTP/FTPS & SFTP (ssh), as well as Amazon S3, and Strongspace (a file storage site ExpanDrive is affiliated with that offers secure storage).   After configuring credentials, the remote site appears as a drive and can be accessed through any program on the Mac or PC on which ExpanDrive is running.  It's incredibly convenient to be able to see Amazon S3, or the Drupal directory on a remote Linux system, or a patch directory on a server as if it were any other network or local drive.

I'd been a longtime MacFUSE user before discovering ExpanDrive.  MacFUSE is an implementation of FUSE.  FUSE is "Filesystem in USErspace".  FUSE implements a generic virtual filesystem driver in Kernel that presents an API for user-space implementation of  specific filesystems.  People have created filesystem modules that implement filesystem views over a wide range of creative underlying storage.  From filesystems that allow you to use Googlemail's mailboxes as a storage system to a filesystem that allows you to write Cache On Write (COW) images, to filesystems that allow access to NTFS under Linux or Mac OS X there are a wide variety of FUSE filesystems.  The one I've used most often is one that allows the viewing of a remote system connected via SFTP(ssh) to be used as if it were a drive.  It was very slow, but still very convenient.  Also, setup required issuing commands at a shell prompt - something I'm perfectly comfortable doing, but also something that has the potential to slow down my workflow.

The first version of ExpanDrive I tried was built upon MacFUSE.  It facilitated access to FTP/FTPS, SFTP(ssh), Amazon S3 and Strongspace.  I had initially downloaded it because of the S3 capabilities.    It was quite a nice interface, and although I initially used it for S3, I quickly discovered that it offered benefits for SFTP connections (as well as FTP/FTPS).  It's graphical, easy to use, provides a convenient menubar menu (on the Mac) to access it.  It manages all the credentials and details of the connection so that mounting a remote system is as simple as clicking on it and a drive appears on the desktop.  ExpanDrive makes MacFUSE functionality accessible and convenient.  It allows convenient use of remote file repositories in a familiar disk paradigm.

Shortly after my purchase, ExpanDrive announced a new version (2.2.2) for the Mac.  This version is not dependent on MacFUSE, and is much faster. My only real complaint about the current version of the product is that it doesn't provide a way of setting S3 permissions.  Apparently, at one pointthey had such support, but it was broken by a Mac OS X upgrade. ExpanDrive support (which is very responsive, BTW) has reassured me that there will be support for this in an upcoming minor version upgrade.