This is a hidden tool for some people something they simply did not know about, but Microsoft does allow commercial (not logo use) of there clip art and photo images. If you have Office, then you have this tool – the Microsoft Clip Art Gallery.
Access the Gallery from Start> Microsoft Office > Microsoft Office Tools > Clip Art Gallery. Then go online and load up your Gallery with new neat free images and sounds at http://office.microsoft.com/en-us/clipart/default.aspx. You’ll love the selection. Just add the items to your basket and then click download and run to load them onto your disk.
We use these free images for blogs, websites, and newsletter content. The EULA states that you can use them for commercial web use, but not for logos or things that are proprietary to your business. But that means you can use them for website images, brochures, and so much more.
Updated as of 7-14-18: Microsoft no longer supports the Clip Art Gallery. There may be other free images resources available online. One to consider may be PikWizard.