Interarchy 8 is the standard in file transfer software for Macintosh users running Mac OS X.
Interarchy supports pretty much everything you can imagine: long file names, long URLs, long files, automatic and manual mirroring, Dashboard widgets, Automator actions, Bonjour, AppleScript (including recording), FTP, SFTP, HTTP, WebDAV (including iDisk), Amazon S3, ping, packet sniffing, you name it, Interarchy can probably do it, all with a user interface designed to keep you productive.