Although the Japanese often improve on many of our gadgets, replacing the dirt in an ant farm with a nutrient-rich gel doesn't quite work as well as you'd think. Instead of digging tunnels and generally surviving, the gel ants in this Antquarium live only a short time by feeding on the dead flesh of their brothers and sisters. Great if you're trying to find who the most survival-worthy ant is, lousy if you're trying to keep them as pets. [Amazon via Tokyo Mango]
There's one of these on thinkgeek that I had a few years ago. The ants lasted about 3 months, and they don't just feed on the dead ones (they actually don't eat the dead at all...they are dragged to a "burial zone" to keep disease away), the gel itself is the nutrient, which they absorb/eat by digging their tunnels for a nonexistent queent.