Below are a few resources for keyword density, however, I'd like to start off by telling you that keyword density is useless! You really should review this article by Dr E. Garcia called Keywiord Density of Non-Sense. After a quick review of that article you'll understand how so called "keyword density" couldn't play any respectable role in "relevant" search results; yes a very true statement. www.keyworddensity.com/ www.webconfs.com/keyword-density-checker.php www.linkvendor.com/seo-tools/keyword-density.html www.seochat.com/seo-tools/keyword-density/
I agree with ssandecki! I used to use a keyword density tool. But they are too time consuming. Now, I just know my sites' keywords and I go by faith when writing content. This speeds up things and makes my site more true to keywords at search engine result pages. However, I do recommend using a density tool when starting out so you can go through the same thing as I did. Submit Express has a good one. On keywords, I just make sure that the links pointing to my site have the popular keyword phrases. My advice to beginning SEOs is to review the keywords you like often, to memorize them for future page content.
In general writing content naturally would cover that. I would say not to worry much about this. Keyword density becomes a major issue when you are fighting for a competetive keyword; then every little thing helps.
For me, I highly recommend GoRank.com...it is really an effective SEO site for checking your keyword density and prominence.
Just get IBP, i HIGHLY recommend it because it gives you everythin you need to know about your site including keyword density....