Cassius Marcellus Coolidge's iconic images of dogs playing poker (or pool) have captivated audiences for more than a century. They have been oft modified and parodied, including these geeky variations:
Ewoks playing poker by deviantART user IC Kessler.
Ewoks (who fail to understand the wisdom of letting the Wookie win) playing poker by an unknown artist. (via Cool Star Wars Photos)
Cylons playing poker by Anthony J. Cox.
Slivers from Magic: The Gathering playing poker by Tom Jenkot.
Classic horror movie monsters playing poker by Fiona Staples
Modern horror movie monsters playing poker by Ray Frenden. (via SuperPunch)
Wolverines playing poker by Paolo Rivera (via SuperPunch)
Marvel Comics heroes playing poker by Andrea DiVito.
Inuyasha characters playing poker by deviantART user ladybattuosai
Classic Nintendo game characters playing poker by Mike Mitei.
Cartoon sidekick dogs (Muttley, Krypto the Superdog, Dynomutt, and one other) playing poker by Ken Cursoe (via Popped Culture).
Computer dogs playing poker by deviantART user ~Smaggers. Thanks to Drew Northcott for the tip.