TreeView X is an open source program to display phylogenetic trees on Linux, Unix, Mac OS X, and Windows platforms. It can read and display NEXUS and Newick format tree files (such as those output by PAUP*, .
Archaeopteryx is a software tool for the visualization, analysis, and editing of potentially large and highly annotated phylogenetic trees.
FigTree is designed as a graphical viewer of phylogenetic trees and as a program for producing publication-ready figures. As with most of my programs, it was written for my own needs so may not be as polished and feature-complete as a commercial program.
Researchers studying phylogenetic relationships need software that is able to visualize rooted phylogenetic trees and networks efficiently, increasingly of large datasets involving hundreds of thousands of taxa.
