Nesta is a lightweight Content Management System, written in Ruby using the Sinatra web framework. Nesta has the simplicity of a static site generator, but (being a fully fledged Rack application) allows you to serve dynamic content on demand.
Content is stored on disk in plain text files. There is no database. Edit your content in a text editor and keep it under version control (most people use git, but any version control system will do fine).
Nesta (and this web site) was designed and written by Graham Ashton, with help from you (the users) who have been submitting patches and sending feedback.