Reveal.js - A framework for easily creating beautiful presentations using HTML
DisplayFusion - DisplayFusion will make your multi-monitor life much easier.
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.
WindowGrid - Quickly and easily layout windows on a dynamic grid using just the mouse.
Google 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.
Mizage Divvy - Divvy is an entirely new way of managing your workspace.