If you use this link to subscribe to Kindle Unlimited and borrow and read unlimited books for no extra charge beyond the subscription fee, you’ll not only see the current deals available (at the time of writing, they were offering the first two months free!), I’ll also be paid a small bonus by Amazon at no extra cost to you!
This link goes to the US site, but if you live elsewhere and KU is available in your region, there will be a link through to your local site.