Avogadro - Avogadro is a free, fantastically easy to use molecule editor.
BioEdit - Biological sequence alignment editor
UCSF Chimera - UCSF Chimera is a highly extensible program for interactive visualization and analysis of molecular...
UGENE - UGENE is free open-source cross-platform bioinformatics software
Jmol - Jmol is a free, open source molecule viewer for students, educators, and researchers in chemistry...
DNADynamo - DNA analysis, cloning and sequencing software