Product review (5 stars): GE Filter Wrench
Works Perfect!  I should have bought this a long time ago.  It turns out the "O" ring on the filter housing was decaying a bit, and that is why the housing was stuck and I could no longer remove the housing by hand or with other 'methods' I had used previously.  This wrench loosened the housing no problem.  A must have item.

Also, you should buy the replacement "O" ring for your filters.