Browsing:

"Keypad +" -- Will Expand the branch you have selected.
"Keypad *" -- Will Expand all the selected branch's sub keys.
"Keypad -" -- will Collapse the selected branch.
"Up Arrow" -- Selects the previous key.
"Down Arrow" -- Will Select the next key.
"Left Arrow" -- Will Collapse the selected branch and if it is not collapsed; otherwise, select the parent key.
"Right Arrow" -- Will Expand the selected branch if it is not already expanded; otherwise, selects the key's first sub key.
"End" -- Will Select the last key that's visible in the key pane.
"Home" -- Will Select My Computer.
"Page Up" -- Will Move up one page in the key pane.
"Tab" -- Will Move between the key and value panes.
"Page Down" -- Will Move down one page in the key pane.
"F6" -- Will Move between the key and value panes.

Others:
"Delete" -- will Delete the select branch or value.
"F1" -- Will Open up the Regedit's Help..
"F5" -- Will Refreshes the key and value panes.
"F2" -- Will Rename the selected key or value
"F10" -- Will Open Regedit's menu bar.
"Alt+F4" -- Will Close the Regedit.
"Shift+F10" --Will Open up the shortcut menu for the selected key or value. 

Searching:
"F3" -- Will Repeat the last search.
"Ctrl+F" -- Will Open the Find dialog box.