Keyword density entire site

Most keyword density tools just look to the url you give it. They don't crowl an entire site with all its subpages. Is there such a tool or site available?

No and for good reason: search engines don't rank entire websites. They rank individual web pages. The keyword density of your entire site is useless information.

So what if I wanted to know what are, let's say, the top 20 of keywords which are most used to access a site?

I can't check through my stats which keywords have been used the most to access my site. But I was curious whether it was also possible to find out such a list from other sites.

Counting the keywords used on one page of such a site would be useless. Wouldn't I have to know the most used keywords on subpages too? When I enter a keyword in a search engine which directs me to a subpages of such a site, cause it has been used the most on that subpage, I would have to now the keyword density of the entire site not only the main page, would I?

If you don't have site stats you should get some. Google Analytics and free and doesn't require installing any software.

Google Webmaster Tools can also tell you the top 20 searches that you rank for.

No. What you're looking for is not keyword density. It's keyword relevancy. To find out where subpages rank in the SERPs, and thus what keywords they are deemed relevant for, you'll need to use a rank checker. There are lots of them out there.

BTW. keyword density is a red herring. I wouldn't worry another second about it.

Can you give me some examples of sites/tools which show the keyword relevancy of a given site? (having trouble finding some).

Do the crawl the entire site or just the main page?