Avogadro - Avogadro is a free, fantastically easy to use molecule editor.
BioEdit - Biological sequence alignment editor
ImageJ - and Other Health Care
UGENE - UGENE is free open-source cross-platform bioinformatics software
TrueChem - TrueChem is software designed specifically to control and automate the management of chemistries, coatings, and wet processes.
DNADynamo - DNA analysis, cloning and sequencing software