What is the smartest thing your cat has ever done?

I was asleep in bed, about 2am, when Spider (My cat) came into the bedroom, placed his mouth by my ear, and Miaowed, LOUDLY. I woke up, suddenly, and not too happily! I tried to push him away, but he repeated himself, then stood up and walked to the end of the bed, and looked back at me. When I tried to lie down, he came back, caught my hand in his mouth, and gently, but firmly, pulled me towards the door. Eventually I gave up, and got out of bed, as he ran to the bedroom door, paused, looked back at me, and waited until I followed him.

Eventually, he got me to the French doors in the living room, where he sat, looking at me and then at the light switch, until I turned the light on to illuminate the patio outside. There his baby kitty sister was sitting, in the rain, not coming into the house. I called her, but she just looked at me, until I opened the door, and picked her up. Although she was purring madly, her leg was swinging oddly, and it was obviously badly broken. I pushed her gently into a basket, pulled my clothes on, and called for a taxi to take me to the emergency vet.

Without his intervention, she would have been stuck outside for at least another five hours, in the pouring rain, badly injured. The vet said that, without prompt attention, she may well have been dead by morning. Spider had saved her from, at best, considerable pain and suffering, at worst, a painful and cold, wet death. It took considerable surgical skill to save her leg, but without him, she may well not have had that chance. He was a lovely cat; He died aged 18 of acute kidney failure, and I miss him a lot!