Impersonator lets administrators impersonate other users. This is useful in cases where you need to check the permissions of editors and other users, if you don't have, or want to know their passwords.
When Impersonator is installed, and you are logged in as an administrator user. You get the option to impersonate another user, by rightclicking their node in the user tree.
When impersonating another user, the avatar in the top left, also shows your regular avatar, as an indicator of you impersonating another user.
Hat tip to Casey Neehouse for the original code. Logo is inspired by the icon Impostor made by Luis Prado.