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.