Mount SSH/SFTP or FTP accounts as if they were local files.
MacFusion is an open source Mac application that allows you to work with files on servers across the internet, as if they were sitting on your computer. Macfusion presents a Volume in Finder, letting you use your favorite Mac applications to work with them. Macfusion works with SSH/SFTP and FTP servers.
More generally, Macfusion is a front-end to Gogole's MacFUSE software. Macfusion provides a plugin API to enable the creation of plugins for other FUSE filesystems.