Removing the applications you do not use also help improve your Mac’s efficiency and performance. By doing this, you, too improve your performance because all the junk and unnecessary files have been moved into Trash and you do not have to scan through them to find what you need.
In addition to this, you can also look for applications that you installed with your printer, scanner, digital camera, etc and remove them if you don’t use them. You might also have beta or expired programs you used and did not like, remove these, too.
Many things come preinstalled with Mac and you probably don’t need these, too. These things include iTunes, iPhoto, iDVD, iMovie, iCal and many other applications. You can certainly delete these if you do not use them. Similarly, any other thing on your Mac that you do not use, get rid of it.