The idea for any sort of solitaire game would be to keep players within the structure of BrainKing and not to send them to Yahoo.com or Pogo.com where they may end up finding other turn based games or multi-player games that they prefer, then not bother to come back.
Personally i think a Feature that should be in development are multi-player games (Froglet is a great example of one).
The idea is to improve BrainKing, not help other sites :o)