There is an anonymous editor that has been editing from 6x.y.z.w for several months now and who is very much interested in various things related to Croatia, mostly people from Croatia and locations in Croatia.
The IP addresses resolve mostly to adsl-x-y-z-w.dsl.bcvloh.ameritech.net, though occasionally it's different, like the below wickliffe.lib.oh.us address (a public library).
The edits are numerous and generally informative, though they tend to over-link (creating gobs of redundant and/or ambiguous links) and mess up interpunction. Because of this, the pages need to be copyedited and sometimes even cleaned up. Other users have often added pages to Wikipedia:Cleanup because of this.
It's so far been impossible to track them down and get them to register.
See also User:Elf#The_anonymous_Croatian_editor.
I've posted the call to register at:
Hopefully I'll be able to catch them while they're in progress and persuade them to register... --Joy [shallot]