Rocky Mountain Ruby 2013 was at the end of September this year. I taught a workshop on writing external DSLs that was fun and difficult to put together. You can look through my class notes, if you are interested.
I also gave a short lightning talk on Muskox, a small library I’ve been working on. The talk’s up on Confreaks / YouTube now, which is awesome. The TL;DR is that populating input data structures willy-nilly from some generic language like JSON or especially XML can be dangerous, so you should prevent bad data from entering your system during parsing.