Search Engine Forums, SEO Forum

Today I have been inspecting the sites of my competitors, and the SEO methods that have been helping them reach the first page of Google for my keyword. To make the page more keyword rich in content, I have found some really interesting findings, with some you can use a method to write text in a DIV that includes tags. Silly methods have not been used, like having the text in same color as background, but instead by putting text in tags, the text has been hidden really smartly. What do you think about this? Any help on this would be great.

What is the benefit of it? To achieve the keyword density? I think that 5-10% is optimal density. If you go enormously above this you can be ignored from google.