Bio-Rad is offering the KnowItAll Academic Edition software absolutely free to the academic community. With this software package, you can draw structures, perform IR and Raman functional group analysis, and generate high-quality reports. Direct link to download (after registration).
ACD/Labs (Advanced Chemistry Development) has just released version 8 of ChemSketch. This software has a freeware version that can be used by students and teachers for academic purposes. Click here to download the freeware version (registration required).
An excellent compilation of ready-to-use applications: 3D coordinates for chemical structures, calculation and 3D visualization of orbitals, VRML and GIFs of chemical structures, calculation and visualization of IR and Raman spectra, calculation of physicochemical properties and many others.