From Greg Mankiw's Blog: On the right are excess reserves of the banking system. Just below is the monetary base. Go ahead and click on them.
People always ask how today's crisis differs from what happened during the Great Depression. Ladies and Gentlemen I give you exhibits A and B (with thanks again to Phil for alerting me to these graphs). During the Depression the line for the monetary base was as flat as it could be. Now it could not be more vertical.