'a D3 plugin for visualizing time series. Use Cubism to construct better realtime dashboards.' Apache-licensed; nice realtime update style; overlays multiple data sources well. I think I now have a good use-case for this

Yes! short-term weather prediction and dataviz. I've been vaguely considering ideas along these lines recently, but these guys have gone much further. US residents, fund it -- I really hope this gets made and makes it to Ireland...

'an open source JavaScript library that produces produces interactive, zoomable charts of time series. It is designed to display dense data sets and enable users to explore and interpret them.' quite pretty

"How the Giants of Finance Shrank, Then Grew, Under The Financial Crisis". but the data is less interesting than the excellent dataviz technique used to display it

'View real-time data and statistics from any logfile on any server with SSH, in an intuitive and entertaining way', supporting postfix/spamd/clamd logs among loads of others. very cool if a little silly