Whenever I'm at a Flea Market or Antique Store of some sort I keep my eye out for old LIFE Magazines, LOOK Magazine or New York Magazines - publications of that ilk tend to have wildly inspiring typography, wonderful photography and even some interesting articles. They also can serve as a nice repository of art to use in new projects, if you're willing to push that copyright boundary a little bit (let's be honest, it happens a lot).

Google Books has a massive archive of LIFE magazines, scanned in and ready for your perusal. It's not quite as fun as digging through a random crate at a Flea Market but there's no lack of inspiration to be found.

You can go all the way back to 1935 or as recent as Dec 1972.