I blogged Sara’s Petri-dish-culture-soaps back in March, and then again a couple of weeks ago when she started selling them through Makers Market. Now she’s just added a couple of awesome new versions with glow-in-the-dark colonies. You can get GITD green or GITD violet. They ship in a real Petri dish and will set you back nine bucks.
GITD Petri dish soaps from Cleaner Science