The largest and most comprehensive database of chemical literature in the world, covers not only the core areas of chemistry, but related sciences such as biotechnology and toxicology.  As of February 14, 2011, you must use the web version (the desktop client has been discontinued).  All OSU users must register using a valid OSU e-mail account (osu.edu, ohio-state.edu, or osumc.edu)
On-Campus SciFinder Scholar Registration -- Off-Campus SciFinder Scholar Registration