For those of you that don't get it, this is the kind of thing that goes to make the Mac a great platform to live and work. I'm not talking about the combined panel, but the thoughts that go into making useful information and presenting it in a useful way.
In this case, the new WebKit has a diagnostics panel (aka lnspector) that can show the breakdown of elements on a page. Note the use of colour to easily distinguish different metadata types as well as the length of bars showing download time; in addition, the summary bar at the bottom shows which resources take the most data transfer.
Frankly, you don't get this kind of application in a Java app most of the time. Either the coders are too busy worrying about a GridBagLayout just positioning the icons, or they're writing a highly generic capable-of-many-implementations (even though there's only one) adapter factory singleton provider for generating multiple pluggable analysis modules, and then just dumping the information in a JTable.