Last week I rewrote the 6 articles that make up one of my sites to increase the keyword density from 2% and less to between 3.1% and 3.4%.  I published the new changes on the 15th.

The interesting thing, I started to rank for 6 keywords I was not fighting for (with positions of 4, 4, 122, 162,59, and 5 respectively, the 1st and 4th of these have decent traffic, the others get less than 500 searches, exact match) and for keywords that contained misspelling of a word, one of them is actually #1 (unfortunately, between the bunch of them, they don't have even 500 exact match searches a month).

Here are the results 1 week later (you'll notice that 1,2,3,6,7,8 stuck, 11 improved: