Mouse-Over DOM Inspector, v2 Keyboard Reference:

1 / Snaps the Data Window back to the top-left corner of the browser window, taking the vertical scroll amount into account. Also places the favelet back into Freeze Mode.
A / Clone the currently highlighted object and its children. Use the “S” key to append it to another object.
B / Cycle highlighting preference. Gray backgrounds, red outlines and none. MSIE does not support the outline property, so this will toggle backgrounds in that browser.
C / Apply a random background color to the element. Hitting “C” again will restore the original color.
D / Toggle the visibility of the Data Window, displaying the element type and id/class (if found) in the “title” attribute of the element.
E / Toggle object width from auto (fluid) to its original width.
F / Toggle Freeze Mode. The favelet will remain active, but the Data Window will not follow the cursor. This is the default startup mode for the favelet.
G / Toggle the visibility of all the data lists.
H / Hide the currently selected element.
J / Show all elements hidden with the “H” command.
K / Remove all element labels from the page.
L / Label the element with its tag name. Clicking the label removes it from the document.
O / Outline the element with a red border. MSIE6 does not support this style property.
P / Pause the favelet. This will disable the favelet without turning it off.
R / Remove the current element from the DOM.
S / Append a cloned object to the currently highlighted object. Use the “A” key to clone an object.
T / Begining at the HTML element, manually step through the DOM, including non-display elements like META and TITLE
U / Toggle “Always Transparent” mode. When on, the data window will remain at 60% transparency (or a value specified by you in your external preference file.) Not available in Opera.
V / View and edit the HTML source of the current element. You may use this to view the HTML of an element on sites serving their content as application/xhtml+xml, but you may not modify it.
W / Select the parent of the current element. This will allow you to step up through the DOM to the HTML element.
Esc / Exit the Favelet/Cancel Edit Mode
 / Apply changes in Edit Mode
Freeze Mode / The new default mode for the favelet, Freeze Mode, places the data window at 10,10 (the upper left corner of the screen) and prevents it from following the mouse cursor. This mode can be toggled with the “F” key to cause the data window to follow the cursor like v1.x
Parent Node Highlights / When the favelet is in Freeze mode (“F” key) or Pause mode (“P” key), you can mouse over the list of elements that make up the Parent Structure of the current element to highlight those elements.
Child Node Highlights / Works exactly the same way as with Parent Node Highlights. Only element nodes are highlighted, but all node types are displayed. If the element is a text node, its node value will be displayed as the title attribute of the list item.
No Object Notification / Since the favelet does not highlight the BODY or HTML elements when in mouse-over mode, it is possible that no element is highlighted. In these cases, the data window will become transparent. Not available in Opera.
Window Drag / When paused (“P”) or in frozen (“F”), the Data Window can be moved by clicking and dragging from the title bar containing the element name.
Pause for Input Focus / In order to allow for interaction with inputs and textareas on the document, the favelet will go into Pause Mode when one of these element types recieve focus. To unpause, simply click away from the input element, or hit the “P” key. Thanks to Simon for the suggestion.
Highlight Indicator / Cycling through the highlight modes with the “B” key will change the Highlight Indicator in the top right corner of the data window to reflect the current highlight mode. A solid gray square indicates gray background highlights, a square with a red border indicates red outlines and the absence of an icon indicates no highlights.
Edit Mode / In edit mode (“V” key), in addition to the “Cancel” and “Apply” links, the “ESC” key will cancel, and the “ENTER” key will apply your changes. If the site is served as application/xhtml+xml, both keys will close the edit window.
Collapsible Lists / The lists of data displayed in the the data window can be collapsed and expanded by clicking their headings. For example, to collapse the “Attributes” list, click the “Attributes” heading. All of the lists can be opened and closed at once with the “G” key.
Keep In View / The data window will adjust its position to stay within the view port when you scroll vertically. This does not apply when the Data Window is longer than the available vertical space in the browser, such as when an object with a long list of child nodes is highlighted.