While there are tons of lists for both fully loaded and ultra-light touring, it really depends on YOU. What is important for you to have? I certainly don't care about a deck of cards or touch up paint, but obviously some people value that stuff, and more power to them for that. A good rule of thumb for ultra-lighting is to ask yourself: "Does this item have three or more uses?". If it does, then it's probably a very good item to have with you. If it doesn't, you need to weigh the importance of it. Obviously if you're touring and your bike is for some reason prone to breaking spokes, extra spokes and a spoke wrench will be important to you. To the 80lb 19 year old grand-daughter, touring with her 70 year old pepe, maybe not so much.
For me? I find that short tours don't require me to bring cooking gear (and even many long ones - it really depends where in the world I'll be). Even if touring on a $3-8/day budget, I can do that without cooking gear. That said, I can tour on about $2/day with cooking gear. Some items (like a mattress pad) seem questionably useful, but have underlying positives to them. A mattress pad for instance, will keep you cooler in the summer, and warmer in the winter. I never travel without my Neo-Air. A pillow? I personally don't bring or care about. Many people love theirs, and with new technology crafting blow-up pillows that weigh 3oz and take up two cubic inches, I'll certainly re-evaluate that opinion.
I've taken 3 day long tours where everything I packed fit in a 4 liter saddle bag. I've also taken them where I brought 20lb in books, paper, coffee, coffee grinder, French press - you get the idea. Weigh each thing's importance to YOU. After a lot of experience, it comes natural. On a long tour, you'll almost always find it possible to send things home (i.e. if you haven't used something in 2 weeks, why are you carrying it with you?).