There are dozens of online PowerPoint alternatives out there, Prezi being the most popular. Although most are free, you'll be tied to a template that may make it difficult to integrate charts, graphics, and other information you wish to present. The key here is SIMPLICITY. Don't load up your presentation with distracting animations, over-bright visuals, or complicated details.
When presenting information to clients, don't feel limited to bullet points in a slideshow. You've collected data from a variety of sources, so don't feel constrained to a basic powerpoint for presenting. Maps, graphics and charts, infographics, and other audiovisual tools are easy to create now using online tools.