Currently WebInspector.panels is filled inside 'loaded' event handler, so it's hardly possible to add any custom panel. To overcome this, I've moved panels creation into a separate function which can be wrapped to add custom panel instances.
Created attachment 33250 [details] proposed change
Sending WebCore/ChangeLog Sending WebCore/inspector/front-end/inspector.js Transmitting file data .. Committed revision 46222.
What panels do you have in mind? :)
I'm planning to add JS & DOM memory monitoring. Initially I'm targeting on Chrome/V8, but with your help I think I could expand it for Safari/JSC too.
Closing issue to remove from commit queue.