Presentations are almost synonymous with slides, but they really don't have to be: If you're trying something new by leaving PowerPoint behind, why not leave the very concept of slides behind? Prezi lets you do just that by treating your presentation as a large canvas, rather than as a collection of separate slides. As the presentation plays, it pans across the canvas, zooming in and out at your command. Done well, a Prezi presentation can feel more cohesive than a PowerPoint one; when you're finished watching it, you feel as though you got a true bird's-eye view of the subject in question.
If you want to go the Google route, Google Drive includes a Presentation tool. It isn't Flash-based, and it includes an interesting Research sidebar that lets you quickly pull in images and other data from the Web. If you start a new slide and suddenly think, "A quote about happiness would go great here," Google's Presentation tool makes finding, attributing, and inserting such a quote into your presentation trivially easy.
One obvious advantage of using these tools over PowerPoint is that your audience won't have to download an email attachment to view your presentation -- they can just click a link and begin, or you could even embed the presentation within an existing page as part of your website.
Image editing: Pixlr, PicMonkey, and BeFunky
The undisputed king of desktop image editing is, of course, Photoshop. But these days, even Photoshop has an online version, called Photoshop Express. It is a far cry from the desktop version in terms of power, but it can help you get the basics done. That said, Photoshop Express doesn't offer a handy Chrome extension -- not even one that acts as a quick link to the app. That shouldn't stop you from trying it out (it's free), but let's look at two options that do come with Chrome extensions: Pixlr and PicMonkey.