With sites like Pinterest gaining popularity, intellectual property rights to images are a problem. (See The Problem with Pinterest.) I recommend you take a look at Link with Love to help educate yourself–and students if you have them–about intellectual property and copyright law.
FairShare is one of several web apps that will follow your copyright protected content. If you think your content is being used without permission, FairShare is a way to track it.
Start by setting up the content your want Fair Share to watch: your blog, your photos, or any text that you publish. (To track images, you have to enter your name and email in a separate screen. Click the “Learn about FairShare for images” link to do this.)
Provide a URL of a blog feed or whatever the content is you want to track. If you are tracking a static page with no RSS feed, it takes a bit of extra work on your part to create a feed for it. The FairShare Help files explain how to do this. Select the Creative Commons License that you want to apply to your work.
Finally, create an account. You provide your email address, create a password, and complete a CAPTCHA form to get started. Your email address is what FairShare uses to notify you when your text or images are found published by someone else. You must agree to the unreadably formatted terms of service, as well.
There is a paid subscription service with additional features. Once you have an account set up, you can add more sites for FairShare to monitor.