As part of the effort to combat sockpuppets and spam evaders, it would be useful to have a tool that allow account administrators to look up accounts by e-mail address.
Ideally, this should also allow to look up by wild cards (possibly regex?). The output should ideally include both username (with link to profile), e-mail address, and age of account (and possibly e-mail verification and "last login" dates).
See also "We don’t really have any great tools yet to find this people nor deter them." from summit 19 notes.