I saw Dawn Of The Dead the other day, I recomend it. I'm a huge fan of the original too, and this one works just as well.. but doing different things with it.
Anyhow.. on that note, I should mention archive.org. Home of The Wayback Machine, which is what most people know it for (basically they archived the web - check out your old websites.. or famous ones. Can be interesting). However they also serve as a general digital archive.
Now, the copyright on the original Night Of The Living Dead expired recently. What does that mean? Well it means you can download the whole movie for free in most modern formats, from streaming Quicktime, to DVD quality mpeg4.
Its pretty big (anywhere from 248mb to 4.1GIG - depending on what format you choose), but damn.. its a classic.
Also on there are things like old Three Stooges movies, or the classic goverment information films like Duck And Cover. Really worth checking out. The free music section is great too, because it not only has old stuff.. but new work created especially to be given out under open liceneses.