The best place for Adsense on your blog
This one comes directly from Google via their Adsense blog:
How can you ensure that your ads are relevant to a specific post? With section targeting, you can target an ad unit to a specific section of the page, as well as block out irrelevant sections such as the navigational links.
Click the link above to above to see all of what Google has to say about this, including example images of optimal placement.

heh… you know… I didn’t know you could put 3 ad units and one link unit per page… I thought it was 3 total units…
Comment by Chris Beasley — February 1, 2006 @ 11:22 am