It seems there is one advantage to having the completely useless foreigner registration number: Google hasn't released it and nobody could use it for anything useful even if somebody got a hold of it.
Google Exposes Thousands of Korean ID Numbers
There's a lot of google-hating going on here in Korea, much of it completely undeserved. The Korean internet is a ghetto where non-Korean search engines are systematically excluded in favor of inferior local search engines (a nightmare for researchers - when I look up stuff online through Google, I'm likely to get pretty similar search results to what I get from yahoo, or ask, or dogpile . . .the rankings or organization might be different, but I'm going to find most of the same stuff. On the other hand, if I'm searching for something in Korean, I'll run it through on Google but then I have to search on Naver or Daum and get totally different results, which is pretty darned annoying to have to do.) The place is littered with active x. But perhaps most vexing, the Korean internet requires your citizen registration number to do anything from set up a blog to shop to make train reservations. All foreigners who are here for more than 90 days have to register and get our own alien registration card and number, but they don't work for anything. I can't make a train reservation (another reason for not making the Chuseok trek to Daegu) or buy movie tickets online or do . . .well, just about anything.
The people to blame for this kind of sensitive personal information getting out and online isn't Google - it's the Korean websites requiring too much information with not enough security. Thank God my information is too worthless to be used for anything.