Here's a site for novice PowerPoint users and elementary school teachers looking for some new ideas. Pete's PowerPoint Station
offers three stops on your resources exploration adventure.
Pete's Presentations houses links to premade PowerPoint presentations for teacher and student use on a wide variety of topics. A collection of free clipart is also available.
Greta's Games organizes links to interactive and instructional resources by topic/subject. so you may find some current favorites in the list. Resources include a variety of formats including PowerPoint and pdf files in addition to the flash player based interactive sites.
Hanna's Help provides resources for improving research skills and utilizing search engines. PowerPoint templates for student projects are also available at this stop along with tutorials for improving your PowerPoint skills.
Many sites leave the Pete's PowerPoint Station site to increase the offerings. Watch for the related links to Google powered ads and search results if you feel adventurous.