No, you may not blog to raise money for yourself, nor for your own charity (except in very exceptional cases, such as with a well-established, registered charity). Additionally, you may not use the Blogathon or your participation in the Blogathon to profit in any way from the event. This includes auctioning off web services or other products for your own gain, using your participation to drum up clients for your own business, or otherwise incorporating Blogathon into any profit-making endeavors.
Blogathon is a not-for-profit event dedicated to helping bloggers raise money for charities; any efforts to use Blogathon to profit personally will result in removal from the event. However, if you normally have advertising on your site, you do not need to remove it for the Blogathon.