Tip: If you download extensions as .zip files, you probably need to rename the file to change the file extension to .oxt.
You can use the clker.com plug-in to easily import royalty-free images from their online catalog. The extension adds a button on the OpenOffice.org toolbar. When you press the button, a dialog box comes up where you logon to your clker.com account. Then you're able to browse through the contents of your saved clker basket, press the copy button, and paste the selected image into your document.
Don't forget about Microsoft's clip art and media. If you have a valid license to a Microsoft Office suite or program or a product that includes Microsoft Clip Gallery or Organizer, you can use Microsoft's media that's loaded on your PC or download content from the Office Online site. When you have the Microsoft Clip Organizer open, select the media you want to use with OpenOffice.org, click the down arrow on the left of the thumbnail, and select Copy. Then paste the media in an OpenOffice.org application.