Blokus is an abstract game with extremely simple rules that I suspect is rather deep that I recently played and enjoyed.
blokus strategy blog - blokus strategy and tactics articles.
duo to the death - blokus duo strategy
blokus discoveries - blokus puzzles, investigations...includes the blokus puzzler, a java applet with a solitaire mode for solving puzzles or planning strategies. Also allows for online play. www.gottfriedville.net seems to be interesting in general.
pentobi - open source Blokus clone for PCs (linux/mac/win). Has an AI at multiple levels of difficulty
pentolla - play a blokus-clone online. This seems to have replaced the official blokus online game.
official blokus.com - decommissioned by Mattel. used to have online play. Forums are overrun by spam.
blockfuse - android blokus clone.
There used to be an iOS blokus game but I can no longer find one.