One technique that's been gaining popularity lately is to strategically position images above an AdSense ad or link unit. See the Wolf-Howl blog for examples of this technique.
Some AdSense publishers go to great lengths to make their images blend quite well with the ads in order to deceive users into clicking on ads without realizing that they're ads. This is bad practice, of course, and the blog entry Images above ad units and complying with the AdSense terms has a good discussion of how it should be done in order to avoid displeasing Google.
Note, however, that Google keeps experimenting with different ad types and sometimes instead of showing a set of small text ads you'll see a single large text ad in one of those ad units, and those images you've lined up so nicely with the individual ads won't look as good anymore. You're still better off to focus your energies on writing good content, in my opinion.