If you are an Amazon Prime member and have thought about trying out Kindle Unlimited, it's currently being offered at 3 months for $0.99. As far as I can tell, you can cancel at any time and there's no requirement to continue beyond the initial 3 months. The offer is good until July 31.
I'd been thinking about doing the one-month free trial, but this is even better. Only problem is that I'd then do nothing but read KU books for three months which would inevitably result in my TBR pile growing instead of shrinking!