Here are a bunch of recommended software tools, many of these I use daily with great success. Think of this as the ”Coleman Filter” for software apps. The listed/reviewed softwares have received my stamp of approval.
FreeBSD - Great UNIX-like operating system. Available for many architectures.
Mathomatic - Pretty nice, fast, small-scale Computer Algebra System. Not as many features as Mathematica (though some may call it bloat).
xup - Free software programmer for Spartan-3E Xilinx FPGA development boards. We just received ours to play with!
graphviz - Free graph/chart/diagram generation software for your computer. You describe the graph and this program builds it for you.
Firefox - Version 3 was just released. Get it now!