What's Keeping Me?
10.6 or later. Did you ever have the problem where you can’t empty the Trash or eject a disk because something is preventing you? Usually the reason is because some application has a file open, and thus you can’t get rid of the disk or trash the file. What’s Keeping Me will identify the application that is preventing you from accomplishing your task. You can then quit, relaunch, or kill the problem application so you can get on with your business. What’s Keeping Me includes an Automator workflow so you can perform searches directly from the Finder too!

SpotlightMetadata
10.5 or later. This lets you see the metadata that Spotlight is collecting on your files. This is helpful so you can better understand how it works and use it more creatively/accurately. We use it to better our own programming techniques. It’s really simple to use and you can get the metadata from a folder of files or target just one particular file. It supports multiple windows so you can perform multiple queries.

Math Practice
Math Practice will help a young person learn the four basic math functions; addition, subtraction, multiplication, and division. It was made as a teaching tool for a young student. This program tries to make the learning simple and fun too.