You may already be familiar with the folks at iStockphoto. They supplied 1000 high-resolution images for inclusion with CorelDRAW X4. And when you registered, they gave you credits towards the purchase of more images.
I know users are hesitant to create accounts sometimes because they don’t want to get extra e-mail. I can’t remember when I created my iStockphoto account, but it was probably at least two years ago. I do get 2-3 e-mails a week. Some are purely promotional, most have something of value. For example, one of them tells me about the free image of the week. That’s right, once a week you can download a high quality image for free! Some of the images will be something you can use, others will be interesting though not useful in your line of work. I just make sure to download all of them and store them in a folder just in case. Once a month they also offer a free vector illustration for download.
Yes, you’ll need to create a free account to download the freebies. I think it is a very fair trade-off to get the free images and illustrations.