ChemSketch

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 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. The freeware version of ChemSketch does not include all of the functionality of the commercial version.

The difference between ACD/ChemSketch and ACD/ChemSketch Freeware:

Option	Freeware	Commercial
ACD/Dictionary	No	Yes
Search for Structure in Different Computer File	No	Yes
Restricted Version of ACD/ChemFolder (SDfile Viewer)	No	Yes
Export to Adobe® PDF	Yes	Yes
ACD/Tautomers	Yes	Yes
ACD/Name Freeware	Yes	Yes
ACD/3D Viewer	Yes	Yes
ACD/I-Lab add-on for ACD/Labs Online	Yes [must be installed separately]	Yes
Instructions for Authors	Yes [must be installed separately]	Yes
Advanced drawing tools (polymers, Markush, reactions, and other features made available in versions 6–10)	Yes	Yes
ACD/Labs Extension for ChemDraw	No	Yes
ACD/ChemCoder 2D barcode capability	No	Yes
Technical Support	No	Yes

Source: http://www2.acdlabs.com/download/chemsketch/chemsk_tech.html

Here are the preview of the software:

For more information, you can click on the links provided below:
ACD/Labs.com
ACD/Labs.com (Freeware)
The Chemical Database Service
Chemsketch - An Introductory Guide