I left desktop apps behind awhile back. I love Google's apps, and except for at work where Office is the standard, I use Google Docs, Calendar, etc, for everything. Everything except Slide Presentations.
I use slide shows a lot at work, and I'm a pretty heavy user. I like to use animations and special effects, and if I needed to show to be portable, Powerpoint is the de facto standard, and a USB drive could move my presentation into any setup. Google Docs "Presentation" is woefully inadequate in that regard, and to share, it requires someone to have a google account, or requires me to sign on to what might be someone else's computer to display it.
Amidst about 1,412 booths at SXSW, hawking various social media analytics tools, SlideRocket was a pleasant find. It's really easy to use, and allows both imports and exports from PowerPoint. Some Most animations didn't transfer over, and had to be rebuilt, but it does at least allow for great interoperability if the situation calls for it. For a visual geek like me, it has a number of unique animations and effects that aren't in the standard PowerPoint toolbox, and, unlike about 75% of Powerpoints, they don't come off looking cheesy in a business presentation.
Ready for your presentation, but you have to present from a different computer? SlideRocket allows your shows to be published to a public link, or even embedded on your website or blog.
... wow.
For me, the extra online features, and unique styling makes SlideRocket an EVEN MORE compelling product than anything from Microsoft thus far. Of course, not everything is free. They have free and paid accounts, depending on your needs. The one feature I think my experience with SlideRocket leaves me begging for is an online presentation mode, that allows me to walk someone else through my slideshow as they view it. 90% of what I see on GotoMeeting and the like are PowerPoint presentations, and with that feature, I could drop that service as well.
So seriously, try it out and see how it works for you. I'm amazed at how far web apps have come, these days, and for anyone who makes presentations regularly, you'll be glad you gave it a try.