I've been working on my first real NPM package, a template engine called Squirrelly. It supports filters, helpers, precompilation, autoEscaping, etc., and works with ExpressJS. It's also faster than the other template engines I've benchmarked it against, like Pug, Dust (most times), Handlebars, and Marko.
Unfortunately, though I've worked on it for a long time, I don't think anybody at all uses it :(.