…is a computer chess engine that you can use in ChessBase Fritz or Shredder (see GUIs). Simply install it as an UCI engine through the corresponding menu option. The current version scores about equal with the strongest commercial engines from 2002 and is therefore a good candidate for the best available freeware engine. Download here.
List achieves its strength through a very knowledgable and well-tuned positional evaluation, combined with an extremely fast tactical search. Here’s an example of List’s king attack capabilities, which is of course just a small part of List’s positional knowledge: