With this small plugin, you can customize your "New tab" page to show the current time and the external ip address. The external ip address is determined with the ipify.org service.
In order to use the plugin, you need to download it. You can do this via git clone, or you can download the latest version here. After that you have to unpack the directory and can upload it via the developer mode in the extensions manager. You can find instructions here.
Thanks to JetBrains for supporting me with this and other open source projects!