The Genealogical Proof Standard (GPS) consists of 5 elements:1) reasonably exhaustive search 2) complete & accurate source citations 3) analysis & correlation of collected information 4) resolution of all conflicts 5) written conclusion.See More
GRAMPS is a Free Software Project for Genealogy, offering a professional genealogy program. GRAMPS currently runs on Linux and Windows. Guides for installation on MAC OS X, BSD and Solaris are available.
Any software that helps Geneaologists, assuming it's going to be mainly Family Tree software, but if there's anything else that can help genealogists with their quest to uncover their ancestors, and extended family, lets add it in here too ;)