I've been running Google AdSense ads on this blog for some time now and am even about to recieve my first check (ooha!), but there are a few things I wish for.
1. Sometimes Google is feeding no ad units at all and the placeholders become ugly gaping holes. While Google lets you pick an alternative image to fill in the placeholders, it would be nice if the script allowed collapsing them altogether.
2. On individual post pages, contextual targeting works great. On the main and archive pages with many regularly updated posts, the targeting often breaks down. The blog is about advertising and Google seems to recognize that, but when I write about a new Sharp dual-view display, I get fed ads for discounted LCD displays.
3. Reporting for individual ad units would be nice, too, so that publishers know if Google Links are as useful as the standard text ads.