The Amateur Radio Relay League (ARRL) is America's amateur radio association. Founded in 1914, it's been an advocate for ham radio enthusiasts, publishing one or more publications about amateur radio theory and practice since its inception. Just today, the ARRL announced that they've made PDF copies of every article they've published from 1915 through 2004 available for download in PDF format.
This is a trememdous accomplishment for the ARRL, and its also wonderful for hams everywhere. Because of the association's rich publishing history, many of the articles in its current publications reference landmark articles in issues that were published ten, sometimes even twenty or thirty years ago. As a new ham, I don't have a personal library of past magazines (and I wouldn't have the space—or the indulgent spouse—to store them all). Making these articles available electronically, for free with a current membership, is a tremendous bonus. Kudos to the ARRL!