Perhaps this is something for you.
Read the rules first
Special Offer for Yahoo! Small Business customers.
Sign up for Google AdWords and receive $50* worth of targeted advertising.
*Valid only for new Google AdWords customers with self-managed signup. Offer based on a $55 total credit, which represents $50 of advertising credit and a $5 activation fee. Advertisers will be charged for advertising that exceeds the promotional credit. Advertisers will need to suspend their ads if they do not wish to receive additional charges beyond the free credit amount. Subject to ad approval, valid registration and acceptance of the Google AdWords Program standard terms and conditions. Offer is non-transferable and may not be sold or bartered. Offer may be revoked at any time for any reason by Google Inc. ONE PROMOTIONAL CREDIT PER CUSTOMER. The advertising credit is only available for orders submitted through the URL provided in this promotion.
Taken from the google website