As a medicinal chemist I would like to have a quick look at the 3D pose of my new designs or organic molecules. Hence looking for the software which can convert 2D into 3D and can also do energy minimization.
An easy place to start is using Avogadro. This is a cross platform builder / editor with a molecular mechanics energy minimization function. It can read the output and generate input for more robust computational programs such as GAMESS and Gaussian. The item can be downloaded for the appropriate operating system at http://avogadro.cc.