There is a new kid on the cheminformatics block.
ChemSpider Beta went live on Saturday March 24, 2007 with over 10 million compounds. Anyone using other free online molecular databases (like eMolecules or Chemistry Search Lookup Service) should definitely give this one a spin.
At this time, it is possible to use the system not only to find molecules in databases but also to predict molecular properties (like density and boiling point), which can come very handy.
But the best reason for keeping an eye on this one is that it is led by Tony Williams. I have known Tony since my graduate student days at the University of Ottawa, where he was running our NMRs. Lets just say he's a little obsessive about the projects he takes on and likes to push the envelope. That usually makes things very interesting.
ChemSpider is still under construction and new features are getting added daily. Make sure to provide some feedback on the site for new features that you would like to see added. Projects such as these are exactly what we need to lubricate free and open science.
Also make sure to subscribe to the accompanying Spinneret Chemistry Webzine written by David Bradley.
I am on the advisory board representing the academic side.