Many school districts have filters that block slide show sites (as well as many other useful sites, but that's another story). My own district blocks Slide.com. So, for a few more options, check these out.
Each of these include photo storage & some version of slide show making. And they're all free! (click on icon to visit site)
SlideShare is really primarily to upload your PowerPoints or other types of presentations online. Then you can post them to your website, blog or elsewhere. But, you could use it for photos too.
There are many other slide show sites. Please share if you have other free sites that you like using.