Hindsight - It's a tracker of "when something happened". Easy to swipe and create a new instance. Has an Apple Watch app also. I at first used it for keeping track of when I took certain medication but now I use it to track other things also.
If you print labels regularly then the following app is awesome. I use it for preparing mailing labels for items I sell on eBay and the alignment is perfect for the selected label sheets I use.
If you need a list application that goes way beyond the basics then I would recommend the following. I've used it for years and it is actually very powerful even if it doesn't look the sexiest of apps. I just wish it offered a simpler sync method such as iCloud instead of the developers custom method.