What is your top 'non-essential' backpacking gear item ?

I am looking at creating my backpacking kit. I just wanted to know what people consider their top items in their backpacking kit that might not be considered "essential" (tent, clothes, cookware, etc) or what they'd recommend looking into to improve the (already great) backpacking/camping experience.

Note : alcohol is supposed to be 'non-essential' !