While poking around SlideShare, I found this set on the 25 Styles of Blogging. I thought it would be a useless bit of fluff, but skimmed through it. Turns out, it's a good quick introduction to different approaches to blogging -- particularly useful for someone who wants to get into this writing life but isn't sure what the focus of their blog should be. I'd recommend using this for Intro to Blogging classes or as a reference link.
SlideShare as a whole is worth checking out; it's essentially YouTube for slide presentations. Neat stuff.