The Internet Archive is a great source of public domain material including quite a few old pulp sf magazines. They even have rare titles, like Super Science Stories which was edited by some young whippersnapper named Frederik Pohl. They only have two issues available so far, Volume 1, Number 2, from May, 1940, and Volume 2, Number 2, from January, 1941, but they feature stories by some famous authors.
The May, 1940 issue has tales by Robert A. Heinlein (writing as Lyle Monroe), L. Sprague de Camp, C. M. Kornbluth, James Blish, Manly Wade Wellman, Donald A. Wollheim and others, including an essay by science writer Willy Ley.
The January, 1941 issue has fewer famous names, but includes stories by the incomparable Leigh Brackett as well as by Pohl himself (as by James MacCreigh) and an early collaboration between Pohl and Kornbluth along with Dirk Wylie, with the story attributed entirely to the latter.
If you're a fan of Golden Age SF it goes without saying that you won't want to miss this stuff. [via Marooned]