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Basic Meta Tags

<meta name="description" content="A description of the page"><!-- Short description of the page. Sometimes used as a part of the snippet shown in the search results. -->
<meta name="google" content="notranslate"><!-- Specify when website translation into another language by Google is not desired -->

Search Engines
<meta name="robots" content="..., ..."><!-- Control the behavior of search engine crawling and indexing, applies to all search engines -->
<meta name="googlebot" content="..., ..." /><!-- Google specific -->
<!-- "Robots" meta tag values:
"noindex" - prevents the page from being indexed;
"nofollow" - prevents the Googlebot from following links from this page;
"nosnippet" - prevents a snippet from being shown in the search results;
"noodp" - prevents the alternative description from the ODP/DMOZ from being used;
"noarchive" - prevents Google from showing the Cached link for a page;
unavailable_after:[date]: lets you specify the exact time and date you want to stop crawling and indexing of this page;
"noimageindex" - lets you specify that you do not want your page to appear as the referring page for an image that appears in Google search results;
"none" - is equivalent to noindex, nofollow; -->

Cache control 
<!--  Defines how pages should be handled by cache. It is specifically used by Internet Explorer browser -->
<meta http-equiv="Cache-control" content="public"><!-- may be cached in public shared caches -->
<meta http-equiv="Cache-control" content="private"><!-- may only be cached in private cache -->
<meta http-equiv="Cache-control" content="no-cache"><!-- may not be cached -->
<meta http-equiv="Cache-control" content="no-store"><!-- may be cached but not archived -->

No longer in use
<meta name='keywords' content='your, tags'>
<meta http-equiv="pragma" content="no-cache"><!-- Since Internet Explorer version 5 they stopped supporting the tag. This metatag was used for caching, meaning storing a webpage locally. -->

Discouraged

<meta http-equiv="refresh" content="5"><!-- Refresh page automatically after 5 sec. Downgrades UX, Back button confusion -->
<meta http-equiv="refresh" content="5; url=http://example.com/"><!-- Redirect to the specified location after 5 seconds. -->
<meta http-equiv="refresh" content="0; url=http://example.com/"><!-- Redirect to the specified location immediately. -->

<!-- The Meta Expires tag defines the expiration date and time of the web document that is being indexed. However this tag does not work with Google,
and the page will be cached anyway. It is better to use cache-control tag. -->
<meta http-equiv="expires" content="Wed, 26 Feb 2004 08:21:57 GMT">
<meta http-equiv="expires" content="0"><!-- Disable caching -->

Read more: http://www.webmarketingnow.com/tips/meta-tags-meta-expires.html#ixzz2bHLwhqnd

sources:
Google Webmaster Tools on Meta tags: http://support.google.com/webmasters/bin/answer.py?hl=en&answer=79812
kevinSuttle gist: https://gist.github.com/kevinSuttle/1997924
Lance Pollard list: http://code.lancepollard.com/complete-list-of-html-meta-tags/#basic-html-meta-tags