Well here are two things I'm working on to give people ideas....
1) I currently working on a app that will let me know how much gas will cost me based on the price and amount of gallons I need to fill up so I'll already know exactly how much when I role up to the gas station. (This is pretty easy, nothing too complicated)
2) I'm also working on 1on1 NBA math adventure game for kids where they can chose a player and they will get some info on the player (such as some of their key strengths and stats). The game will include the top 15 NBA players. (A little more complicated)
How it goes is...
A) They choose one player and they play a 10 game season.
B) Each player has a certain arithmetic lesson tied to him (Camelo with addition, Lebron with mutiplication, etc.)
C) Each game consist of 5 math questions and each question they get right count as a point.
D) The better the player they face, the tougher the questions.
E) Basically the kid navigates their player to a championship by answering all questions correctly.
I got the idea from a co-worker whose kid loves basketball but suck at math, lol.