Special:CheckUser is the IP-to-username checker Tim Starling implemented
for en:. Those able to use it are him and me, and I hardly dare touch the
thing :-)
There's talk of allowing it on other Wikipedias. There's a discussion page
at [[m:CheckUser]] and some of the tinfoil hattery makes my head hurt. I
would welcome contribution from those who already have this power and more.
Particularly for "What circumstances merit checking?" which is the big
question for me. I've been *very* conservative in using the tool, possibly
too conservative, and am looking for guidelines to a sensible policy
guideline.
- d.