CACTUS NIH Chemical Identifier Resolver: access to chemical structures in 2D and 3D from their name (common, commercial or systematic) or their ID (SMILES, InChI, CAS).
cactus.nci.nih.gov/chemical/structure
Two versions, using Java or without it. The Java-less version also includes the functionality of "Jmol Direct"(see below).
A facilitated portal biomodel.uah.es/quimica (uses Jmol built-in access to CACTUS)
Access directly pubchem.ncbi.nlm.nih.gov
or from the NCBI portal (formerly Entrez) 
