" I recommend everyone to sign up for wikipedia.com [...]"
Just redirect wikipedia.com to bnaibrith.org, they'll assume WP has been taken over completely and give up. More ambitiously, mirror the database from wikipedia.org, allow them all to create accounts and edit as usual, but update articles from wikipedia.org each night. They'll go crazy trying to figure out why only their edits are disappearing daily, including attempts to communicate with other users.
Even more evil, heh-heh, make them register with real name and address and credit card number if they come in through wikipedia.com, and charge them for editing the mirror. It's a .com, right? and we're supposed to be filthy money-grubbing Jews, right? Just think of the poetry in having very dumb neonazis funding the next round of server purchases...
:-)
Stan