Slideshare, VoiceThread, and Prezi are online presentation tools that can be used as alternatives to PowerPoint. Slideshare allows users to upload and share PowerPoint files, documents, and videos. It has over 18 million uploads across 40 categories. VoiceThread allows comments and discussions on shared files and presentations, integrating various media formats. Prezi uses a zoomable interface that allows users to zoom in on details and pull back to reveal context. While these tools offer unique features, educators must monitor students' use to prevent inappropriate content from being shared.