There is also a good cleaning tool that I use myself, it's called Ubuntu Tweak, great tool. To install it, do:

sudo add-apt-repository ppa:tualatrix/ppa 

This will download the PPA repository, then you can go into Ubuntu Software Center and let Software Center do all the magic. Or you can do it all by command line (which is what I prefer) and use these commands after the PPA is loaded in your repository:

sudo apt-get update   

sudo apt-get install ubuntu-tweak  

Open the Dash and type Ubuntu Tweak then open Ubuntu Tweak with a click.