ChemSketch (ACD Labs)
ACD/ChemSketch Freeware is a drawing package that allows you to draw chemical structures including organics, organometallics, polymers, and Markush structures. It also includes features such as the calculation of molecular properties (e.g., molecular weight, density, molar refractivity, etc.). 2D and 3D structure cleaning and viewing, functionality for naming structures (fewer than 50 atoms and 3 rings), and prediction of logP.
Marvin Sketch (ChemAxon)
MarvinSketch allows users to quickly draw molecules through basic functions on the GUI and advanced functionalities such as sprout drawing, customizable shortcuts, abbreviated groups, default and user-defined templates, and context-sensitive popup menus.