Copying other people's ideas
Quite often I get people write to me and say, Hey Joe, (I'm sick of that one for a start,) is it okay if I use your background on my site? No, it bloody isn't!!! The background and graphics elements I created for my site give it a unique graphical style and they won't be unique if other people start to use them. And their sites won't be unique because they used the style of another well known site.
Using the visual style of any other site, especially one with 100,000 visitors each month, is going to do you more harm than good professionally.