I just took advantage of a sale at Wolfram Research to buy Stephen Wolfram's A New Kind of Science bundled with the companion software A New Kind of Science Explorer. The bundle is available for about the same price as the book alone at, say, Border's, which never heard of discounting the price from the MSRP. I am enjoying the book, reading some sections carefully and skimming others. The software, based on Mathematica, is limited to what is done in the book but it is organized nicely so that it is easy to read about a topic in the book and the immediately go to the relevant section of the software, indexed by page number, to try it out and experiment a bit with variations in initial conditions, depth, or what have you. Highly recommended.
I wrote (enthusiastically) about Mathematica in a previous post. It is also worth noting that Wolfram is not universally popular among his peers. Compelling ideas served alongside jealous gossip: what could be better?