If you're interested in astronomy then you might enjoy this PBS documentary, 400 Years of the Telescope.
This beautifully filmed show summarizes the history of the telescope beginning with Galileo's first experiments with looking glasses up to the Hubble and radio astronomy. Along the way it (briefly) describes various recent technologies like adaptive optics and techniques for building very large mirrors.
While not a deeply technical resource, it is a nice way to spend an hour. In my case, I watched this on my iPhone while waiting for my son at a doctor's appointment and it was much better than reading out-of-date magazines - well worth the $1.99 cost.
Watching this made me want to work in an observatory someday, maybe I've seen the movie Contact too many times (if that is even possible) :-).
