On DesignShack.com Jake Rocheleau has a tutorial showing you how to create an image uploader that pushes the image over to the Imgr service.

In this tutorial I want to demonstrate how we can remotely mirror an image found elsewhere online and auto-upload to Imgur. It’s possible to create a form handling user-uploaded images as well. But I wanted to keep the demo clean without needing to move user content onto the server. This process is very simple once you understand how APIs work.

He provides all of the code and guidance you'll need to get the system working. It uses a simple HTML layout, some jQuery for submitting the image data back to the the server and a PHP script to call the Imgr API. It uses curl to make the call, so you'll need that extension installed to use the example. You can check out the live demo or just download the source to get started quickly.