I've found a great site where you can download public domain Golden Age comics.
To the best of my knowledge these are all public domain and therefore legal to download and since the site launch in 2006 there's been no legal contact from companies. seems it's all above board.
One note - since this is public domain you won't find comics from DC, Marvel, Archie or any other companies still in existance. However, if you want to experience other superheroes of the Golden Age or some old horror or romance comics this is your chance.
The Golden Age site was down for a while due to some kind of file corruption. It just went back up today, and it seems to work fine. In case anyone was interested in checking this out.
I gave it a try today, and it's quite an interesting look down memory lane. Pretty much all the comics are legal, as far as I can tell. Most of these characters are in the public domain anyway, so they're free and clear. Interesting stuff.