This is the app to turn to if you need to free up drive space.

It's one of those utilities that is incredibly useful when you need it most. It opens all the most common archive formats as well as older formats (such as StuffIt) and can also get the data out of other kinds of files, including some Windows. This small app is a great tool if you work with compressed archive files. It tells you how much available memory you have and will flush your RAM with a single command, freeing up space that may have been previously used by other apps. If you're trying to get the very best performance and can't afford to fully upgrade the RAM inside your Mac (or even if you can), Memory Clean is essential.