Web traffic from spelling mistake

Today I just realize that, one of my popular pages, http://money.softbath.net/stock, has a big spelling mistake which I dont intend to do so !

The correct keyword should be "Hang Seng index" which is the stock market Index in hong kong. But I spell it wrongly and use "Heng seng index" instead.

Surprisingly, I check the site stat and find that much of the traffic comes from this wrong keyword ! It was amazing to grap these traffic by accident.

I know wrong spelling keyword has been some special common practice in search engine marketing, but I have never tried it. Now I was inspired to use more of this technique on purpose to see if I could gain some extra traffic from it...
:P