You can add other ones but those are the most important for search engines.
Here are the ones that we are using for our home-page:
<meta name="description" content="Frozen Interactive specialise in website design in the UK for small to medium businesses. We create user friendly, accessible web site designs that can easily be self edited without any fuss." />
<meta name="keywords" content="web design London, accessible web site design london UK" />
<meta name="author" content="Frozen Interactive Limited" />
<meta http-equiv="Content-Language" content="en-uk" />
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
Chris.