American Heritage magazine's, Invention and Technology. American Heritage has gone through some rocky times but it is back in print again. Invention and Technology has also suffered in recent years as its sole advertiser, General Motors, pulled out because of its own financial problems. But Invention and Technology is back and the magazine still provides excellent articles on the history of technology.
American Heritage has made all of the past articles from Invention and Technology available free to the public on their website. You can find them here. It is well worth your time to browse some of these stories. Better yet, buy their magazine on the newsstand. You won't be disappointed.
[Disclaimer: I have no stake, financial or otherwise in American Heritage or Invention and Technology.]