What are some alternatives?
When comparing LaTeX Beamer and Prosper and Keynote, you can also consider the following products
LibreOffice - Impress - Impress is a truly outstanding tool for creating effective multimedia presentations.
Prezi - Welcome to Prezi, the presentation software that uses motion, zoom, and spatial relationships to bring your ideas to life and make you a great presenter.
Sozi - Sozi
Powerpoint - Explore how PowerPoint can help you tell a powerful story in your presentations and easily share your slides on the web.
Google Drive - Slides - Create a new presentation and edit it with others at the same time — from your computer, phone or tablet. Free with a Google account.
Powtoon - PowToon is a brand new presentation tool that allows you to create animated presentations and cartoon style videos just by dragging and dropping.