What's wrong with using a local FTP server hosted on your Mac OS X machine?
The protocol has been around forever, and even built into 68k Web-browsers. The Transmit client is excellent. And CrossTalk FTP is a full-featured, java-based FTP server.
CrossFTP doesn't support segmented downloads, unless it's been added recently? I couldn't find any reference to it being added.
http://www.crossftp.com/forum/viewtopic.php?f=3&t=7848
BitKinex is indeed fast & supports segmented downloads.
Apparently, you can use FTP with it (I think). That said...I have no idea. I had no idea until I just looked it up. I don't know about SSH though.
Quote from their FAQ page:
> Q: What can I do with Amazon S3?
> Amazon S3 provides a simple web services interface that you can use to store and retrieve any amount of data, at any time, from anywhere on the web. Using this web service, developers can easily build applications that make use of Internet storage. Since Amazon S3 is highly scalable and you only pay for what you use, developers can start small and grow their application as they wish, with no compromise on performance or reliability. It is designed to be highly flexible: Store any type and amount of data that you want; read the same piece of data a million times or only for emergency disaster recovery; build a simple FTP application, or a sophisticated web application such as the Amazon.com retail web site. Amazon S3 frees developers to focus on innovation, not figuring out how to store their data.
So I'm not 100% sure. Further research required.
EDIT^(1)| Random links on the subject: