Mathematica is one of those packages that seems to make enthusiasts of its users. I'm neither mathematician nor user enough to give an opinion on the recent release of version 6, which is said to be the biggest revamp for nearly two decades. But I can say Mathematica's British-born founder Stephen Wolfram wrote one of the most interesting books I have read in the past five years (read my review).

If you can't afford Mathematica 6, or indeed if you can, you can get an idea of what the product can do at a new website called The Wolfram Demonstrations Project, a growing collection of open-code "mini-applications" and contributed by users worldwide. You can run them in a web browser, but if you want to play around with the parameters you have to download a free Mathematica player. The 1,300 demonstrations currently posted include a dynamic visualisation of a double helix (above left).