I've just added the Make Poverty History to my website. Visit the website to know what it's all about (more geared toward the UK). The code is free to use, you just need to add it anywhere in your page. I put it in the gutter and there it is:
<script type="text/javascript" src="http://www.makepovertyhistory.org/whiteband_small_right.js">
</script><noscript><a href="http://www.makepovertyhistory.org/">
http://www.makepovertyhistory.org</a></noscript>
A similar website with similar objectives is one.org, worth a visit, worth a help. Here is the code for the small banner i have added to my gutter:
<a href="http://www.one.org/"><img
src="http://www.one.org/images/banners/ONE_150X150_01.gif"
width="150" height="150" border="0"></a>
Many other banners, bigger and smaller, in their website.