Macfusion is an app for OS X (obviously) that allows you to mount FTP and SSH connections as though they were drives on your Mac. Though not a heavy use tool, Macfusion is quite nice for making quick and dirty updates to websites. When “mounted” all the files on your web server act as though they are on your computer, which means you can directly edit them. Just make sure you download a backup first, because that is a very quick way to screw up a website.
Did I mention it’s free?
I hear there are some problems with Lion, but if you follow the trail on the Macfusion Github page it will work just fine. They recommend downloading and installing the only dependency, MacFUSE from this site, rather than the copy from Google.
As a side note, FTP seemed quite sluggish for me, to the point where it was nearly unusable, but when connected with SSH it’s quite speedy,