Somehow I hosed my PowerPoint installation on my computer, so I uploaded a few presentations to Google Docs. But Google Presentations really sucks--quite basic and clunky, and doesn't import from PowerPoint well.
I remembered a bunch of online PPT generators came out a few years ago, so I did a quick search of TechCrunch and came across SlideRocket.
SlideRocket is great online presentation software. I was able to create, edit, and share my presentation very quickly, and then share the link. The graphics are slick, the interface is generally easy to learn and use, and the quality seems great.
The free account limits sharing and export, so I'll likely pay for a month of use soon. I highly recommend it, though I think the pricing is a bit high at $240/year.
That's about what Powerpoint costs, and it's very cheap for me to simply reinstall it and then use SlideShare for sharing my slides.
Regardless, SlideRocket has been a big help. If they drop their entry pricing to something more reasonable, I imagine they could really take off.