I haven't written one, but I contributed a few patches to nanoc [1]. But if nanoc didn't exist, I probably would have written my own.

And now that you mention it, I have been looking for an excuse to learn Clojure...

[1] http://nanoc.stoneship.org/

I have done some quite significant static site generation without ever having to write a static site generator from scratch - although I did have to make changes to the core of Hakyll to make it use ByteString so I could efficiently process the amount of data I needed (I contributed the changes back and they are now an official part of Hakyll).

Contributing to an existing architecture is definitely the way to go if what is already there is flexible enough to do what you need.

I think it's a good idea for everyone to write one. I wrote one as a sort of hello world project that has a very tangible output.

It's almost like a web 101 test to pass or something.

A proof of some kind of competency with the web stack.

I did, and I'm like the worst programmer ever. So yes.

It's the new guestbook.