Apple - What's a good graphical SFTP utility for OS X?
Cyberduck (Free)
A great free FTP client. This is my go-to application. Anytime I need FTP access, I use Cyberduck. It's not quite as lightweight as Fugu, but it adds a lot more functionality than Fugu. I also really like the Growl integration with Cyberduck.
Fugu (Free)
Awesome little FTP client. As I noted above, this is a lightweight FTP client. It is great for simple FTP transfers and browsing. I do like the dual panel navigation.
EDIT: I forgot to add these.
Filezilla (Free)
I haven't actually used Filezilla extensively, but from what I've seen of it, I really like it. I downloaded it and played with it for a bit and I really like the tabbed connections. I also like the ability to jump to a path easily.
RBrowser (Free, $29 Upgrade)
A free FTP/FTP-SSL client. I don't usually use RBrowser because a $29 upgrade is necessary to unlock other protocols (Local, FTP/SSL/TLS, SFTP-SSH). I do like the Site Manager. It's a handy little thing to have.
I searched and came up with some other free FTP clients:
FireFTP (Free) - Firefox extension
The one downside I see is that this is for Firefox. The website doesn't make it clear how it works with Firefox, so I assume it is an extension.
Macfusion (Free)
This one relies on Google's MacFUSE. Since I don't know anything about MacFUSE, I don't know if this is good or bad.
Transmit ($34) By Panic
I have never used Transmit before, but I have used Coda and I definitely would recommend anything from Panic. The only reason I haven't used this because of the $34 price tag.
ForkLift2 ($30)
Never used it, just found it when searching.
Fetch ($24 per user)
An amazing program with a long, long, long mac heritage. It's way up there with Transmit by Panic and Interarchy as a file transfer program loved by long time Mac power users.
Flow ($30)
Never used it, but looks good from the screenshots. I really like the fact that it looks like Finder. I may have to give this one a try.
OneButton FTP (Free)
Just searching around and found yet another one...It looks pretty nice, except it's no longer supported. However, you can still download it.
Transmit
Panic's Transmit tops my list. An extremely well built and executed FTP Client that fully supports sFTP. Priced at $34.
Transmit is an excellent FTP (file transfer protocol), SFTP, S3 (Amazon.com file hosting) and iDisk/WebDAV client that allows you to upload, download, and delete files over the internet. With the most Mac-like interface available, Transmit makes FTP as simple, fun, and easy as it can possibly be.
Forklift
Forklift 2 is another terrific client that is just as solid and just as well built. Priced at $29.95.
ForkLift will connect to any remote server FTP, SFTP, Amazon S3, WebDAV, the SMB, NIS and AFP shares on your local network, or your Bluetooth mobile phone- pretty much anything you can plug into or hook up to a Mac. ForkLift also carries a complete toolbox for managing your files, including Folder Synchronization, Batch Renaming, Archive handling, Application deleter, editing files over remote connections and many more. All these power features are packaged into a Finder-like, dual-pane interface that delivers superior workflow while remaining absolutely familiar to use, along with QuickLook, Spotlight search and all.
Cyberduck
Lastly, Cyberduck rounds out the list. It is not as well polished, but it sturdy and does the job. It is free.
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such as Spotlight, Bonjour, Keychain and AppleScript are built-in.
There are others to be sure, but these are the one's I've used and personally recommend. Additionally, you may want to hit up places like MacUpdate, VersionTracker, or iUseThis for these types of questions. You will find much more diversity and get a better understanding of the programs available to you.
ExpanDrive
ExpanDrive acts just like a USB drive plugged into your computer. Open, edit, and save files to remote computers from within your favorite programs—even when they are on a server half a world away. ExpanDrive enhances every single application on your computer by transparently connecting it to remote data.