I've just finished converting this site and blog over to using markdown for its content. I'd been using ReST for work and nearly went with that but decided I slightly prefer the syntax used by markdown.
I really hope this kind of thing catches on; HTML is so ugly and not particularly suitable for writing content. Writing a blog in markdown just feels a lot more natural - like I can just get on with the writing and not have to think about how it will look on a web page.
If only code could be like that! I've had a number of moments of fancy when I've thought it would be great to have a programming language that looks like english. I've tried out a few ideas but never really come up with anything that would keep me totally happy. The best example I've seen of this kind of "literate" programming language so far is Inform 7, which I've dabled with a little.
I still have some ideas and might consider breaking a few of them out again.
I think I'm unecessarily obsessed with dreaming up toy languages. (See obfuna)