There's also a horror movie poster style take on The Trouble with Tribbles:
And a declaration of love for everyone's favourite (barring Klingons) little fuzzballs:
UPDATE: Here's another one, The Tribble Terror, which seems to be a mash-up of the classic TAS promo image with Attack of the Killer Tomatoes!:
These designs join the Tribble Trouble computer game-style design I featured a couple of weeks ago with other video game inspired shirts, as well as a couple of more generic The Trouble with Tribbles designs Trevco have (using stills from the episode), and a tribble-filled QUOGs shirt.
It's generally a pretty good year for wearers of the I love tribbles shirt, with both DST and QMx releasing new born tribbles into the world, and them apparently appearing in some fashion in Star Trek: The Video Game.