How to set the new Tab

Firefox

Reddit thread

Create 2 files inside of the firefox install directory.

${installDir}/defaults/pref/autoconfig.js

pref("general.config.filename", "autoconfig.cfg");
pref("general.config.obscure_value", 0);
pref("general.config.sandbox_enabled", false);

${installDir}/autoconfig.cfg

// first line is a comment
var {classes:Cc,interfaces:Ci,utils:Cu} = Components;
var newTabURL = "http://localhost:8080";
aboutNewTabService = Cc["@mozilla.org/browser/aboutnewtab-service;1"].getService(Ci.nsIAboutNewTabService);
aboutNewTabService.newTabURL = newTabURL;

Replace the "localhost" line in autoconfig.cfg with your URL. Also you can set the homepage via your normal settings.

Alternatively you can use a extentions called New Tab override.

Chrome

Maybe this extention. Not tested yet.