Call it the anti-PowerPoint. Prezi, a Web-based presentation tool famous for its use at TED talks, ditches the venerable slide show in favor of letting presenters swoop in, out and around a giant tapestry of words and images. It’s eye-catching and, in the proper hands, an extremely effective way to communicate a message. Prezi users include businessfolk who might otherwise be driving a PowerPoint presentation, but it’s also popular for digital résumés — Prézumés — and other types of storytelling. The basic service is free; pay a fee and you get options such as extra storage and the ability to make your presentations private.