"gRaphaël’s goal is to help you create stunning charts on your website. It is based on Raphaël graphics library." And that's what I've been looking for.

"If you need to perform data analysis, provide graphics for your users in your webapp, or produce high quality plots I encourage you to investigate the combination of ruby, GSL and GNUPlot." Looks good. I should probably give this a poke some time; could come in handy.

"igraph is a free software package for creating and manipulating undirected and directed graphs. It includes implementations for classic graph theory problems like minimum spanning trees and network flow, and also implements algorithms for some recent network analysis methods, like community structure search." Oh, that could be very handy

"This has to be the most quick-and-dirty data visualizer out there: I wrote an ascii art plotter script that takes a column of numbers on stdin and throws out a plot on your console." Oh, that's going to come in handy.

"UbiGraph is a tool for visualizing dynamic graphs. The basic version is free, and talks to Python, Ruby, PHP, Java, C, C++, C#, Haskell, and OCaml."

"Drawing on inspiration from Plotr and PlotKit, software developer Ole Laursen wanted to bring the same plotting functionality to jQuery. So he built his own jQuery plugin and called it Flot." That looks rather nifty.

Visualisation for looking at your listening history on last.fm. The outputs are beautiful.

Lovely - especially the simpler ones. Would be great in Project Brahe, a little bit of dynamic magic...

Generating nice dynamic flash graphs using php