This demo works for basic data, generic requests ie url=http://google.com don't work

Simple jsonp proxy via node-http-proxy

var http = require('http'),
    httpProxy = require('http-proxy'),
    url = require('url');

// Create your proxy server
httpProxy.createServer(function(req, res, proxy){
    var baseUrl = url.parse(req.url, true),
	query = baseUrl.query,
	server = !!query.url ? query.url.replace(/http:\/\/([^:\/]+).*/i,function(url,server){return server;}) : '',
	port = !!query.url ? query.url.match(/:(\d+)/) : 80;
    if( !server ) return;

    if( port && port.length > 1 ){
	port = port[1];
    } else {
	port = 80;
    }

    req.url = req.url.replace(/\?url=http:\/\/[^/]+\//,'');
    req.headers.host = server + ":" + port;
    console.log(req)
    proxy.proxyRequest(port, server, req);

}).listen(8000);

Example usage:
http://127.0.0.1:8000/?url=http://www.google.com/calendar/feeds/developer-calendar@google.com/public/full?alt=json

Refer to https://github.com/nodejitsu/node-http-proxy#readme to get node-http-proxy running