Cubism.js - time series plugin for D3

Cubism.js is seriously cool JavaScript time series visualization project from Square with support for horizon charts:

… horizon charts reduce vertical space without losing resolution. Larger values are overplotted in successively darker colors, while negative values are offset to descend from the top. As you increase the number of colors, you reduce the required vertical space.

The source is on GitHub, under the Apache 2.0 license.