A specific Narrow-Down Filter using MySQL

Hi,

Check out http://www.landwatch.com/Land_For_Sale

Notice the filters on the left column and how they all have the count of the entries within them. I am sure they are not calculating all these count at the run-time. They have these values stored somewhere and just retrieving the top 5 values. Not sure how this can be done. Any insight?

I hear that datacubes with all these dimensions can give this result instantaneously. But I'd like to think there's an easier solution.

Help!