The first time I got impressed was when MIT decided to put its courseware online for free. That was dubbed as MIT Open Course Ware, now its Popular Science that has done it. The magazine that has been publishing articles on science and technology, has partnered with Google to place there 137 years of data online for free!
Although there is no utility to browse through the issues but with the search facility one can find relevant stuff. Google ADs are included off course. Head on to the Popular Science Archive page and read to your heart’s content.