Skyfall features more than 1,300 shots involving special effects, according to this article by FX Guide, with work by a variety of companies and including miniature work supervised by Chris Corbould.
The article includes a podcast with visual effects supervisor Steve Begg (click here to go direct to the podcast), as well as looking in detail at the work on the train sequence in the PTS, the MI6 explosion, the komodo dragons, the train crash on London Underground, the finale in Scotland and the main titles.