At the grocery store the other day Sarah and I attempted to find shallot for a recipe, but I can't tell the difference between shallot, sweet onions, yellow onions, etc. etc. We found something that we decided was the closest we'd find in the store and I believe we picked correctly because at checkout the cashier rang it up as shallot.
I think this could be a practical problem that the 20q Pocket Mind Reader should be able to solve: obtain the name of an unidentified object. When we got home I decided to test the 20q Pocket Mind Reader on shallot. Unfortunately, it told me I had an onion, but I think if these were designed for identifying unknown objects based solely on information you can obtain by looking at it, rather than requiring knowledge of seeds, where it grows, etc. it would do better. Or I could just ask someone who works at the grocery store.