Applying wood image as background is a nice idea and great to creat nature effect to you website. It is like a trend now. Here are some example :
1. http://www.xeroxaven.com/

2. http://rubiqube.com/

3. http://leslyg.com/

4. http://henryjones.us

5. http://electricpulp.com/blog/

where to get wood stock image?

1. deviantart /wood FREE
2. Go media $14.99