The first place to look for information on Ghostscript and Ghostview is the Ghostscript Home Page. Presumably, this information will be kept current by its maintainers (not us!). There is also a semi-commercial (though unsupported) version, with better fonts, available by mail at a reasonable price from Aladdin Enterprises.
Here are a few, some older, downloading points known to us at the time of writing. You want to get both Ghostscript (often named "gs261..." or similar) and Ghostview (often named "gsview..." or similar) for full effectiveness: