The troublemakers over at Cryptome point to this list of default passwords for routers, servers, and the like. Not all black hat uses.
A couple years ago I used a similar, but much smaller list, to find out the password to a flaky cable modem the local cable monopoly could not fix. Actually, once inside the modem it was clear the problem was not with the modem at all, but rather the local cable monopoly's lines.
Knowledge is power. Admin: admin.