The Bad Meta Tags

Author/Web Author - This tag is used to name the author of the page. It's just not necessary on the page.
Revisit After - This meta tag is a command to the robots to return to a page after a specific period of time. It's not followed by any major search engine.
Rating - This tag is used to denote the maturity rating of content. I wrote a post about how to tag a page with adult images using a very confusing system that has since been updated (See the comments). It seems as if the best way to note bad images is to place them on a separate directory from other images on your site and alert Google.
Expiration/Date - Expiration is used to note when the page expires, and date is the date the page was made. Are any of your pages going to expire? Just remove them if they are (but please don't, keep updating content, even contests, make it an annual contest!). And for date, make an XML sitemap and keep it up to date, that is so much more useful!
Copyright - That Google article debates with me here, but look at the footer of your site. I would guess it says "Copyright 20xx" in some form. Why say it twice?
Abstract - This tag is sometimes used to place an abstract of the content and used mainly by educational pursuits.
Distribution - The distribution value is supposedly used to control who can access the document, typically set to global. It's inherent that if the page is open (not password protected like on an intranet) that it is for the world. Go with it, and leave the tag off the page.
Generator - This is used to note what program created the page. Like author, useless.
Cache Control - This tag is set in hopes of controlling when and how often a page is cached in the browser. It's best to do this in the HTTP Header.
Resource Type - This is used to name the type of resource the page is, like "document." Save yourself time, as the DTD declaration does it for you.