Type 2: Universal binaries. Your Mac has either a PowerPC or Intel processor. Most apps on your Mac are programmed for both processor types. Roughly speaking, they consist of two parts, and you'll always need only one part for your processor, while another one can be removed.

Solution A: If you're an advanced Mac user, you can delete a useless architecture using Terminal.

Solution B: Browse Mac software directories for tools that will cut useless parts of your apps.

Type 3: Interface languages. Most Mac apps are translated into many world languages. It's great that Apple is being international, but hardly any people understand and need more than five languages in their Mac apps. So how to get rid of interface languages?

Solution A: Delete unused languages from the Languages list of the apps' More Info menu.

Solution B: Browse Mac software directories for language removing apps that will do the above job for you.

Type 4: Duplicate files. No one is secured against accidental creation of file copies. In most cases you don't need them, so it'll be wise to remove them.

Solution A: Search for file copies manually. However, this process can be rather tedious and time-consuming. In addition, in most cases you don't know which files have duplicates, and renamed copies make the situation even worse.

Solution B: Browse Mac software directories for duplicate removing apps that will do the above job for you.