Windows only: Process Monitor, our preferred Task Manager replacement, has updated with a host of new features and improvements. What you'll most notice is a new column that can provide aggregate CPU usages of multi-process apps like Chrome.
To check out the new column, right-click in Process Explorer and choose "Select Columns". From the "Process Performance" tab, select "Tree CPU Usage". You'll now see the total processor pull of apps like Chrome that use multiple processes to do their work. Other improvements to Process Explorer include built-in disk and network monitoring, more memory statistics, more reliable DLL scanning and other goodies outlined at the Sysinternals blog.
Process Explorer is a free download for Windows systems only.