My littlest kitty loves heat, and she'll spend hours sprawling on that patch of floor when the heat's on. Rolling, squirming, and embracing the warm air with all four paws extended in a nap. Her fur has polished that floor so slick, it's almost hazardous for us taller folk to walk by.
My poor little kitty, who doesn't really like me and fights with the oldest cat. The one I've often eyed with regret, wondering if I couldn't somehow find a home for her where she'd be happier. I haven't had any success, mostly because I haven't tried very hard out of guilt. But I did realize as I watched her fur waft in the wind from the vent: if she ever did find a nicer home, it would still have to be one with a heat vent. This kitty loves warmth!
I can't make fun of her too much though, because I have to confess: I too have sat on that slippery piece of hardwood floor, leaned against the wall by the vent, and allowed its heat to blow over me and through me, filling me with warmth. Mmmmm.... cozy.