Ask HN: What's Neat in Your Field?

It's amazing what science and engineering have accomplished. But unless you are in a field, you may not know what is possible. What's neat in your field that might make someone else go, "Wow, I didn't know we could do that."?

Prompted by the Ultra Sonic Lens cleaning article submitted here: https://news.ycombinator.com/item?id=34426600