From Ben Spink:
CrushFTP handles FTP, SFTP (SSH FTP), FTPS (FTP over SSL), HTTP, HTTPS, WebDAV, and WebDAV SSL. WebDAV allows you to use the OS X Finder to connect to the server and work on it as if it were another hard drive on your machine. Read, write, rename. all with WebDAV. The built in fully customizable WebInterface allows you to present a website to customers so they can easily upload files to you, or download files to you. It has support for drag and drop uploading on the Web site, as well as the ability to upload folders while zipping them on the fly. This saves time and bandwidth. You can use the browser uploader to queue up file transfers and submit them all at once. Easily setup e-mails to come to you when a user uploads files. You can drag and drop folders on a user to grant them access to the folder. The user will then only be able to access that folder.
Lastly, the plugin support for CrushFTP allows for a whole new set of expandable features. Implements thread pooling to handle high load situations, and faster response times, adds support for SFTP and remote administration, and uses less internal threads for connections.