$subject: subject of the mail
$text: text of the mail
+'LogPageValidTypes': action being logged.
+$type: array of strings
+
+'LogPageLogName': name of the logging page(s).
+$typeText: array of strings
+
+'LogPageLogHeader': strings used by wfMsg as a header.
+$headerText: array of strings
+
'TitleMoveComplete': after moving an article (title)
$old: old title
$nt: new title
'CategoryPageView': before viewing a categorypage in CategoryPage::view
$catpage: CategoryPage instance
+
+More hooks might not be available but undocumented.