Take Transmit, our long standing, very Mac-like FTP / SFTP client.
Then, add a ton of new features, including column view, tabs, a sidebar, new favorites, search, dock status, spring loaded folders, iDisk and WebDAV support, and much more.
The end result? We think it's the ultimate Mac FTP client, with more innovative features than anywhere else, and it makes FTP as simple, easy, and fun as, well, the Mac!
Mac OS X 10.3.9 or higher.