Personally I just use a single keyword target that has <h1> tags around it and the rest I use is content similar to that keyword.
The preferred keyword density ratio varies from search engine to search engine. In general, I think a keyword density ratio in the range of 2-10% would be fine.
It's our experience that key word density is an overated on-page factor. As long as you DO NOT hit the "magic" percentage point it's actually not very relevant anymore. The other various on-page and more importantly off-page factors are the ghost's in the SE machines.
Then what is "relevant" when dealing with the SE. True, anything can be overated if it distracts from other factors to much. But I find it hard to believe that page content doesn't matter at all.
I didn't say page content doesn't matter... I said a specific kwd doesn't matter like it used to. Used to be (and in some SE's still rings true) keyword stuffing worked well. When we produce SEO'd content for sites, we write it for the user... not the engine.
I personally go on 5% for MSN and Yahoo! but 2.5% for Google. That is when I can be bothered to check the keyword density!