I usually keep at least one batch of toad tadpoles a year. I've also kept bullfrog tads a few times, and a couple of leopard frog tads. Leopard tads have nice patterns when they start growing their legs.
I had a giant water beetle larva for awhile, until the cat knocked its container onto the floor and killed it. Thing was huge, probably two inches long. I fed him by sticking mysis on a tiny wire and wiggling it in front of him until he grabbed it.
Anyone know if keeping bullfrog or leopard frog tads in an aquarium would run the risk of transferring/carrying/etc pathogens when they were released? For big tads, I keep them in an aquarium with a floating platform until they have four legs and a small tail, then I move them into a tank with a couple inches of clean water until they're all frogged out. I wouldn't transfer water, I'd just put the frogs in a tank with a damp paper towel and take them to the local river.
Toad tads can't go in a community tank, of course, they'd be eaten. Bullfrog tads are cool, though, and I've seen them at my LFS before. I don't think it would be a good plan to buy them from my LFS (even if they are locally collected) and then release them. So I'd like to catch some wild bullfrog tads and keep them until they grow, but I don't have the spare space for the 10g or so it takes to keep those big things happy and clean.