As you might have noticed, I have put two AdSense blocks on my site (one text-only right next to the laptop image and one at the bottom after the main content, which hold 4 ad blocks). If you get enough traffic on your website, adsense could easily pay for your hosting costs.

I recently found a site I started about a year ago for my NeverLose.net domain. On that site, I had put a funny script that displayed an ad for FireFox with the Google toolbar, but only if the page is viewed with Internet Explorer :)

<!--[if IE]>
      <SCRIPT type=text/javascript><!--
            google_ad_client = "pub-5917468348099026";
            google_ad_width = 110;
            google_ad_height = 32;
            google_ad_format = "110x32_as_rimg";
            google_cpa_choice = "CAEQvfX7zwEaCFQXSPmB2TSqKJOjwXU";
            //-->
      </SCRIPT>
      <SCRIPT src="http://pagead2.googlesyndication.com/pagead/show_ads.js" type=text/javascript>
      </SCRIPT>
<![endif]-->

The script is included below, check this page with IE and FireFox to see the difference :) 

If you want to place adsense on your site, here's my affil link :)