When it comes to making presentations, the gold standard is obvious: Microsoft (MSFT) PowerPoint is so established that the program's name is essentially synonymous with projecting a series of slides. It's the Xerox (XRX) of presentations. But you might not have a copy of PowerPoint on your laptop, or you might the need to build a quick presentation without the benefit of your installation of Microsoft Office. What then? Here are some alternatives that you can use for free, anywhere.
PowerPoint. That's right, the best alternative to PowerPoint is PowerPoint. Specifically, the Office Web App version of PowerPoint. Recently, Microsoft rolled out a full suite of online Office apps which are functionally identical to the $500 copy of Office on your PC. The big difference? They're hosted online and run in your Web browser. Log in with a Windows Live ID, and you can do pretty much anything online that you can do in PowerPoint on the desktop. And it's completely free.
Google Docs. If you want to take a pass on the Office Web App version of PowerPoint, for some reason, you can try Google Docs instead. To be perfectly honest, Google Docs' presentation tool was pretty lackluster until recently, but these days it's quite a bit more competitive. It's still no PowerPoint, but you can definitely make do with it. It now supports templates, transitions and animations, and since this is Google Docs, several people can edit it simultaneously.
Prezi. Though Prezi isn't a traditional presentation tool -- it eschews numbered slides for a giant canvas that you can pan around as if your projector were a magical camera -- it's definitely worth evaluating. It is free (with subscriptions for the pro version that has additional features) and lives online like the other options I've discussed here, but you can also install a player for iOS devices as well. in the past, and it bears repeating that this tool lets you create stunning presentations unlike anything your audience has seen before. And it's not hard to master, so definitely check this one out.