The greatest strength of Joomla is the wide range of extra components, modules, plugins and tools that are available.
But sadly for so many web masters this is also Joomla's greatest weakness. Just because they are there doesn't mean you have to use them.
Please think twice before installing any extension and ask yourself this question.
"Is this extension of benefit to my site, does it offer something extra that my users would benefit from. Or am I just installing it because I can."
I mean, come on people, who needs a clock on a website there is already a clock on the screen without you adding one.