What do you think about Keyword Density for Google? Some people say it should be about 2%, whereas others claim they get high ranking because of keyword stuffing with about 10%. How about Yahoo and Bing, what keyword density should be used for them? Let's discuss.
Give Google 5 - 6 % otherwise it looks just not natural. Make sure you use the keywords in the first sentence
Yes keeping it in limits is important, you cannot be sure that those claiming to get high ranking by 10% keyword density won't get banned or blacklisted by Google after some time when Google finds out what they are doing.
well... you can use upto 5%-6% keywords in your SEO copy. However, this is not only the density that matters for SEO or google. You need to intelligently manipulate your content and make sure your keywords are prominent. This could be bit complicated to explain. Try reading some stuff on SEO Process and some similar pages.