The Firefox Asterisk Revealer bookmarklet reveals the 
contents of any password field (i.e., a field whose text is obscured by asterisks) in an alert box using a simple bit of javascript—particularly handy for those sites for which you’ve saved the password but long since forgotten what it is. The post itself just includes the javascript, but you can turn it into a bookmarklet by simply right-clicking your Bookmarks toolbar and selecting New Bookmark, and then pasting the javascript into the Location field.
Firefox Asterisk Revealer [AKSN1P3R]
