I like the idea of a plaque. I had my most loved cat privately cremated so that his ashes weren't mixed up and have even left instructions in my will for his ashes eventually to be mixed and buried with mine. He was so lovely, and there were times when he knew I was in pain - waiting for a double hip replacement - he would climb on my back, lie down there with his paws around me, lay his cheek against mine and purr gently. This comforted me far more than the pain killers, and he knew what he was doing, these were conscious comforting behaviours. They are far more sentient creatures than some people think. And they bring so much to our lives. He lives on in your heart.