If you are looking for a calculator, be it scientific, statistical, or simple public school level but the RPN and emulating HP/Casio interface makes whatever you found worthless, then this is what you look for.
File management app that let you copy, swap card, and even copy files in batches. On top of that, built-in FTP client.
A complete and easy-to-use mathematical 2D graphing calculator.
Do you feel most checklist tools are too rigid and/or too specific to use? Pen-and-paper is still quite possibly The Method? This tool aims solving that: create list, use 2 types of checkmarks, and optionally let you tag a photo (by file, and by camera if your device offers it)
Crazy Tiles is an adaptation of the game Crazy Eight, but played with tiles instead of cards; game allows single player or two-player duel (includes AI to act as stand-in for 2nd human).