Nobody likes their HTML, JavaScript, or images stolen for use on another site without permission. One of the common ways to prevent this, unfortunately, are JavaScript snippets that stop a user from right-clicking anywhere on the page. The rationale behind this is that if the user can't right click, they can't "Save Image As..." or "View Page Source", or even worse, "Copy Image Location" and steal your bandwidth.
While it might work for casual image thieves, this approach (1) is not foolproof, and worse, (2) will annoy many of your site's users.
Why isn't it foolproof? Well, there are several ways around this limitation (using a menu shortcut to view the page source or browsing through your Web browser's cache, for example), but the most obvious flaw is that it's written in JavaScript. All the Web browsers enable the user to disable JavaScript, rendering your efforts useless.
The more important question, though, is why it annoys your users. Your users are the reason your site exists, so you don't want to annoy them. The right-click context menu contains shortcuts to common browser functions. For example, some people might right-click and select "Back" from the context menu instead of clicking the browser's Back button.
Firefox users in particular will be annoyed by this practice. Many handy Firefox extensions are accessed through the right-click context menu. If you disallow right-clicking, all that functionality is lost for the duration of the user's visit to your page. I myself use a great mouse gestures extension for Firefox that is triggered by the right mouse button. This extension doesn't work either.
So, for the love of your users, don't bother trying to block right-clicks. You will end up annoying users while having a minimal level of protection of your content.
(Photo: herkamer from Flickr)
