I took this to the extreme and did all the math. I got all of the Hugo Award information from Wikipedia's Hugo Awards entries. And I cross-checked that against which stories were available at Free Speculative Fiction Online, which I've found to be pretty thorough. Basically if you find a science fiction story somewhere else online, but the Speculative site doesn't offer it, I'd definitely question the other site's legality and/or legitimacy.
For the purpose of this chart I lumped the Retro Hugos in with the normal Hugos
So that is 180 science fiction stories I can put on my Nook for free. And these are all stories that are considered the best of the best in science fiction.
Now most of these stories are available to view online without download options, but thanks to the wonders of the internet, if you can find the text online, you can also convert it to a format an e-reader can use. Here is a site that offers free online conversion of files. I tested PDF to Epub format and it translated pretty well. Meanwhile, doc format to Epub was perfect. So assuming you have the text of the story on a website, all you have to do is copy the text and paste it into a blank Word document file and you are ready to go! (Thanks to Michael at the Classic Science Fiction Board for suggesting this site)
To me, I think it proves that everyone should get an e-reader of some kind. Otherwise your options are to read off the computer screen which strains most people's eyes, or print the stories out which can get pricey with the cost of ink. It just seems like e-readers pay for themselves because you can download so many stories for free.