Briar Press
/We're sure this isn't news to many of you, but for those who aren't familiar with Briar Press, it's a great resource. As they say "Briar Press is a community of letterpress printers, book artists, and press enthusiasts. The site is dedicated to the preservation of letterpress-era equipment and the art of fine printing."
In addition to their always interesting discussion groups, they have a wonderful image gallery of old letterpress printers, free vector files to use in your designs and a forthcoming museum that will include a virtual collection of presses and pin marks.