A Grid console servlet, that will provide you with all free and busy proxies along with their registration info as a JSON object

MyConsoleServlet

package com.test.MyServlets;

import java.io.IOException;
import java.util.Iterator;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.openqa.grid.common.exception.GridException;
import org.openqa.grid.internal.ProxySet;
import org.openqa.grid.internal.Registry;
import org.openqa.grid.internal.RemoteProxy;
import org.openqa.grid.web.servlet.RegistryBasedServlet;

public class MyConsoleServlet extends RegistryBasedServlet {

	/**
     * 
     */
    private static final long serialVersionUID = -1975392591408983229L;
    
    public MyConsoleServlet() {
    	this(null);
    }

	public MyConsoleServlet(Registry registry) {
		super(registry);
	}

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req, resp);
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		process(req, resp);

	}

	protected void process(HttpServletRequest request, HttpServletResponse response) throws IOException {
		response.setContentType("text/json");
		response.setCharacterEncoding("UTF-8");
		response.setStatus(200);
		JSONObject res;
	    try {
	      res = getResponse();
	      response.getWriter().print(res);
	      response.getWriter().close();
	    } catch (JSONException e) {
	      throw new GridException(e.getMessage());
	    }

	}

	private JSONObject getResponse() throws IOException, JSONException {
		JSONObject requestJSON = new JSONObject();
		ProxySet proxies = this.getRegistry().getAllProxies();
		Iterator<RemoteProxy> iterator = proxies.iterator();
		JSONArray busyProxies = new JSONArray();
		JSONArray freeProxies = new JSONArray();
		while (iterator.hasNext()) {
			RemoteProxy eachProxy = iterator.next();
			if (eachProxy.isBusy()) {
				busyProxies.put(eachProxy.getOriginalRegistrationRequest().getAssociatedJSON());
			} else {
				freeProxies.put(eachProxy.getOriginalRegistrationRequest().getAssociatedJSON());
			}
		}
		requestJSON.put("BusyProxies", busyProxies);
		requestJSON.put("FreeProxies", freeProxies);

		return requestJSON;
	}

}

Just in case if any one is wondering about getAssociatedJSON() method... it's removed. You need to use eachProxy.getOriginalRegistrationRequest().toJson()