Keystone makes it easier to get a blog / website / web app up and running without a lot of the module research or boilerplate code node.js usually requires. It also provides a beautiful, useful admin UI (think activeadmin for rails).
It's open source (MIT), and cool because...
* There isn't really anything like this for node.js yet (that we've found). There are a so many great modules and you can plug in almost anything, but getting projects off the ground requires a lot of boilerplate compared to frameworks like rails or django.
* It makes sophisticated things trivial by providing drop-in patterns - like session management and auth, and clever fields for your models, e.g. location fields and image fields (which make for a better admin UI but don't abstract too heavily the underlying data the fields represent).
* We're trying to build an "out of the box" system that doesn't keep you in the box. You can use what you like and swap out what you don't. You can use Jade or Handlebars. Plug in any express middleware you like. Use the built in auth system or provide your own.
* It's all based on the best practices my team have come up with in over a year of node.js web app development and we're using it to power several commercial, production projects. So it's got real-world usage and solves real problems.
* Quite a few people have said this is a gap in the node.js ecosystem, and ultimately if Keystone is just useful for us and a handful of others that's fine, but it would be really exciting if we could start something that helps node.js grow or helps other web developers use the platform. Especially for projects where rapid development is important, and having a great admin UI available would be the difference between using node.js and not.
If you're interested check out http://keystonejs.com