I find programming languages interesting because they're designed to solve problems the designer thought are important, and understanding a little bit about a different language gives me a little bit more understanding of what the designer was thinking.
The latest programming language I'm dabbling in is Clojure, a LISP on the Java VM.
I'd like to collect what I found useful in learning Clojure later on. For today, I found this exceedingly interesting: Reddit Clone in 10 minutes and 91 lines of Clojure. Interesting because it brought together so many concepts in a short and useful package (rather than, say, yet another calculator example).
Learning a new language is always hard, I find, because there's always a big step up in the beginning before I know enough to do anything even remotely interesting. Tutorials like that helps a lot in learning a new programming language.