The fundamental nature of PowerPoint makes it an ideal selling tool. You have a group of people, stuck in a room, listening to a speaker for an extended period of time -- anywhere from fifteen minutes to an hour or more. This enclosed environment exists only for the presenters to sell something, whether it is a product, a service, or an idea.
However, many presenters, especially those with a corporate interest in mind, fail to capitalize on that environment. Think about it. You have a hundred people in a room. They are all listening to you, but they are also watching the giant screen behind you, staring at the messaging, absorbing the graphics. Make the best of their fixed attention by creating brand reinforcement in every slide.
Using Your Brand
"Brand" is admittedly an ambiguous term. It encompasses and summarizes everything about a company that makes them unique, better and memorable. Elements of the brand can be broken down into various building blocks, one of them being visual identity. A company's visual identity includes things such as their logo, letterhead, tradeshow booth, brochures, website and yes, PowerPoint.
Logo and Slogan
Every single slide should include the company logo, at a minimum. The logo should be unobstructed at all times, and should be large enough to read easily -- never assume everyone in the audience has heard of you or understands your brand. Also, if the company has a slogan, consider building it into the design. This doesn't have to be blatant, but sometimes a repeated phrase, no matter how small or subtle, can have enormous effect.
If possible, the slides should consistently employ the company's corporate colors. If you're McDonald's, use red and yellow; if you're BP, use green. The colors can be part of header and footer graphics, titles or even arrows and bullets. The effect can be subtle, but it makes for a more consistent and professional-looking piece; often, it's small embellishments and attention to details that build brand awareness.
Along those same lines, consider font usage. If you're not distributing your PowerPoint presentation, you have immense freedom of choice in type since you can use any font stored on your local machine. In this case, simply contact your graphic designer to obtain your corporate fonts. These may very well be esoteric typefaces purchased from Adobe or another foundry, so be sure that you have a proper license to use them. (Most fonts come with a license for five users.)
If the file is going to be publicly distributed, you are restricted to fonts that come with Microsoft's default installation. Study your company's collateral and try to match the face as closely as possible. Ask the company's graphic designer for a suggested font.
Photography and Illustration
Often, a company settles into a particular theme with their photography and illustration. For instance, IBM's photography is very straightforward with little or no effects. Microsoft's photography is always full color and usually has smiling people. While it would be near impossible to perfectly mimic a company's entire art direction, it is best to complement the established style as much as possible. This is another case where the small details slowly but surely build ever-important brand reinforcement. Under no circumstances should you use the cringingly bad clip art included with Microsoft's Office suite; at best the stuff is tacky, at worst it cheapens your slide show and corporate brand.
This encompasses the extras that might benefit your audience. For instance, a booth number might be a wise inclusion if you are at a trade show. A URL is almost commonplace these days. For sales-heavy presentations, an e-mail address for the presenter is often a good addition, or the company's toll-free ordering line if you want to be more brazen. Including everything is not necessary -- it's just as important to keep the slide design uncluttered.
If done correctly, a PowerPoint presentation can be a whole branding experience. Without ever directly discussing your logo or font choices, you have successfully educated the entire audience about your visual identity, and that positive reinforcement breeds market awareness.
Maybe they mentally noted your URL to check out later. Maybe they scribbled down your e-mail address to ask a question later. On a more tangible note, an audience member will identify the corporate branding of your tradeshow booth when they walk by; they will recognize your corporate colors, logo and typography. Maybe they don't remember why it looks familiar, but it hardly matters when they stop to talk to a company representative.