Document Publishing
41. MiKTeX
An update of TeX, MiKTeX is a typesetting program with a complete set of fonts, utilities, and macros. According to the original developer, it was "intended for the creation of beautiful booksand especially for books that contain a lot of mathematics." Operating system: Windows, Linux.
42. SiSU
After creating documents in the text editor of your choice, you can use SiSU (Structured information, serialized units) to publish them in the format of your choice and make them searchable. Supported formats include plain-text, HTML, XHTML, XML, ODF, LaTeX, and PDF. Operating system: Linux/Unix.
43. PDFCreator
This tool from PDFForge allows users to create PDF files from any printable Windows document. As an added bonus, it can also create PNG, JPG, TIFF, BMP, PCX, PS, or EPS files. Operating system: Windows.
44. Ghostscript
Written in C, Ghostscript allows users to convert, view, and print PostScript and PDF files. Different versions of the software are available either as open-source or as commercial distributions. Operating system: Windows, Linux/Unix, OS X, Classic Mac.
Education
45. NASA World Wind
World Wind allows users to access satellite imagery to view the entire globe or zoom in on a particular area. It offers a number of different views and gives users the options of superimposing latitude and longitude lines, borders, and place name labels. Operating system: Windows.
46. Stellarium
Why bother with a trip to the planetarium? Stellarium shows you the night skies from the comfort of your PC. In fact, this is the software in use at many planetariums. Operating system: Windows, Linux/Unix, OS X, FreeBSD.
Emulators
47. ZNES
ZNES lets you play your Super Nintendo games on your PC. Some games work better than others, and its very much a work in progress. Operating system: Windows, Linux, FreeBSD, and DOS.
If youd like to play Gameboy or GameboyAdvance games on your PC, give VisualBoy Advance a try. In addition to offering most of the functions you would find on a Gameboy system, this app also makes it easy to find and use cheats. Operating system: Windows, Linux/Unix, OS X.
49. DOSBox
Miss the old programs and games from your x86 system? DOSBox allows newer Windows machines and other operating systems to run literally thousands of older games. Operating system: Windows, Linux, OS X.
50. Wine
Its name stands for "Wine is not an emulator." While that may be technically true, Wine does let you run Windows programs on x86-based Unix systems. It also includes a toolkit for porting Windows code to Unix. Operating system: Linux/Unix, OS X, Solaris, All