At most major libraries, you can go to the reference section and find a publication that references periodicals by topic, and you can research topics as far back as the 1880's for some magazines (like National Geo) or at least back to the 1930's or 1940's. The publication indexes hundreds of different magazines, and it makes finding articles very easy.

Has anyone ever found such a tool on the internet? If so, do major magazines publish on the web their archived issues or articles?

I don't know whether this is exactlywhat you're looking for, but if you click http://www.findarticles.com/cf_0/PI/index.jhtml a link will take you to a website that may possibly be helpful.

Thanks, it's a great site. I was hoping for access to much older articles. The oldest I could bring up here was late 90's. This one seems to have a nice selection of subjects, though. It's nice to know references like this are becoming available.