gistfile1.js

var http = require("http");

var server = http.createServer(function (req, res) {
    // needs to be a big enough file for the download not to finish inmediately
    var url = "http://lolpics.se/pics/1871.jpg";
    res.writeHead(200, {"Content-Type": "application/octet- stream",
                        "Content-Disposition": "attachment; filename='big.jpg'"});
    var file_request = http.request(url, function(file_response) {
        file_response.pipe(res);
        file_response.on("data", function(data) {
            // watch it flow!
            console.log(data);
        });
    }).on("error", function(e) {
        console.log(e.toString());
        res.end("Nope");
    });
    file_request.end();
});
server.listen(8000);