I'd always have liked that I could transfer a file or an stdout/stdin stream directly in the middle of an open ssh session. Also the file transfer / stream should be carried over nested ssh connections.
Imagine that you could just pipe the output from a command into some magical ssh command in a remote machine and your ssh client would ask where you would like to pipe the stream in your local machine.

I knew I shouldn't have asked Wolfram Alpha The Answer to the Ultimate Question of Life, the Universe and Everything.

Now imagine a Beowulf cluster of those...