i dont know exactly what they like, but i know they dont dislike 10%+. test it out yourself just by analyzing serps... searching for hosting, hosting.com has 13%, hostcompare.com has 17% and so on, and they are in the top 10 (depending what datacenter you look at), and i've seen flash websites with only couple of words on the page, making it 20% of course, maybe they only get away with it cause they have quality links with that keyword in text pointing at them, so dont just go stuffing keywords
There is no optimum keyword density. How can there be? 6% means your page is relevant to a query but 6.01% and your page is less relevant? Pages with 100% (and do) rank #1 and pages with 0.001% rank #1. Forget KD and just write good copy for your visitors.
A good way to measure could be if you write an article on a subject and don`t count the keywords before after you are finishing writing. Then you will get a natural %.
I must agree with hooperman and login. Use your energy and time to create natural and orginal copy and not to count words.
it is advisable to use 6 to 8 % for google and just put keywords in such a way that it have some sense.and google will not consider only your keyword density but your title and description must me relevant.just concentrate on your keyword reach content which must be fresh.
I think that KD provide only a very little part of the ranking algorithm. I think placing keyword, keyphrases in heading is enough. Over 3-4% KD the site looks unnatural IMO.
No one can answer that for you. Try it out on a few pages and see what gives you the best results. use common sence.
I want to share a thing with you..you are just waisting your time by trying to figure out keyword density, its just not about what you should worry..if you will pay attention to the keywords, but not to the user who will actually read your page copy, you will loos user and the chance to rank well, if your page sounds robotic for user it will sound in the same way for search engine. You see the secret is that when you dont focus on keywords you actually use them in the best way and besides that you use other related keywords, which will lead you to the good page ranking in other words you satisfied the person who reads what you write and you gain other part of the cake. It doesnt mean that you dont need use your keywords, I mean you should place them in those spots where it makes natural sense..
Dear login if you don't agree at all, please clickon the 1st at this query for the keyphrase "click here". The first result is an adobe page. You should check the keyword density on this site
Also try searching for premium sites http://www.google.com/search?q=premium+sites Our directory is first on the list for 90+M with only two keyphrases! But domain name is important here for shore.