Macfusion is an application which can mount volumes via FTP or SSH based on MacFUSE program.

Though I know this application released few years ago, I didn't trust its stability and had not tried it since its release.

Mac OS X can mount FTP as default, but for some reason I can't understand, upload is not allowed.

Latest version of Macfusion runs smooth and enables accessing to FTP volumes from finder seamlessly. You do not need run other FTP application each time you upload files to your site.