Zen Coding is an utility to generate simple HTML skeleton structures using a path like expression with some syntactic enhancement. From the demos, it is really quite impressive, because in this way one can generate quite quickly complex HTML structures.
I read the entry on slashdot.org and then followed the link to this blog.
Though I still need to try it. I am amazed. I have to make it work in eclipse and emacs (aswell as perhaps vi).