I need an idea for my final project in my C++ Data Structures Class

Based on these requirements:

Any ideas would be appreciated

A game sounds like it would be fun to do, but also anything that would be useful to someone...

The project is any useful program for entertainment, business or personal use that utilizes any form of a data structure(s) of your choosing for storage and processing.
 Data should not be hard-coded into your programs; that is, information should come either from a disk file or from user input to the keyboard.
 Any data processed in RAM using your data structure(s) should be saved to disk storage.

 You will have four milestones:
Assigned Points Task
Week 7: 15 Project Idea, submit by April 25th
Week 8: 15 Preliminary flow charts (if any), UML’s (definitely), documentation of programs involved (names, purpose, connecting programs), etc., submit on May 2nd
Week 9: 30 Rough operating program, with stubs and at least one feature working, submit on May 9th.
Week 10: 40 Rough draft with any documentation, working programs
Week 11: 100 Final project, with electronic and hardcopy documentation of flowcharts (if any), UML’s (definitely), source code for all files and supporting files, submitted by May 16th.