After a bit of research and consideration, I now have a short list of web-based resources I'll use to keep in touch with the state of modern programming. Again, I've tried to be conservative in order to save time and to focus on my learning goals:
I might be able to add one or two more specific resources once my learning languages of choice are finalized.
In order to start evaluating my potential programming languages, I spent a fair amount of time browsing Amazon. Soon, I came across a fairly well-rated introduction to a number of decent-looking languages: Seven Languages in Seven Weeks. All seven listed (Clojure, Haskell, Io, Prolog, Scala, Erlang, and Ruby) are ones I've heard of, but have no experience with so far. It's helpful that there are some functional languages included, since I'm keenly interested in getting up to speed with one.