The adsense program has a number of clauses to make sure that the interests of the advertiser and of Google are being protected. Most of them are to make sure that the viewers the advertisers get are genuine, that Google's good name is not being used in a wrong way and that your actions will not lead to a lawsuit against Google.
* Up to three ad units may be displayed on each Web site page.
* A maximum of two Google AdSense for search boxes may be placed on a page.
If there are any more where do you plan to put in the content buddy?
* No Google ad may be placed on any non-content-based pages. This includes error, login, registration, "thank you" or welcome pages.
* No Google ad or Google search box may be displayed on any domain parking websites, pop-ups, pop-unders, or in any email.
* No Google ad may be placed on pages published specifically for the purpose of showing ads, whether or not the page content is relevant.
Adsense is targetted ads. No content, no traget.
* Clicks on Google ads must not result in a new browser window being launched.
Now this is a weird restriction, but live with it.
* Any AdSense ad code or search box code must be pasted directly into Web pages without modification. AdSense participants are not allowed to alter any portion of the ad code or change the layout, behavior, targeting, or delivery of ads for any reason.
Yeah you may not change the script in *any* way. No you cant even modify the colors by hand. And you surely cant tweak it to open the link in a new window.
* In order to avoid associations with copyright claims, website publishers may not display Google ads on web pages with MP3, Video, News Groups, and Image Results.
Who wants to be sued if they can help it. Google is just being cautious.
* Web pages may not include incentives of any kind for users to click on ads.
So you cant say something like " Click on the links to support us". Such clicks are crap for the advertisers.
* Any method that artificially generates clicks is strictly prohibited. These prohibited methods include but are not limited to: repeated manual clicks, incentives to click, using robots, automated clicking tools, or other deceptive software. Please note that clicking on your own ads for any reason is prohibited, to avoid potential inflation of advertiser costs.
Oh otherwise I would be clicking on my links making money instead of writing this article.
* Site may not include: (.....................)
Basically you cant put anything illegal, immoral or offending on your webpages along with adsense.