Welcome to voovy - Webmaster Tools for Free Website Advertising, Free Banner Advertising, & more!
voovy.com recommends the following websites:
BannerExchange.net - A growing banner exchange network for webmasters that supports 5 of the most popular banner sizes (468x60, 728x90, 125x125, 300x250, & 160x600). This banner network has an affiliate program so that members can earn addition banner impressions. Advertisements are clean and there is no additional advertising or links added to the banners. Members can easily earn a lot of free banner advertising credits.
Below is an Example of a 468x60 Banner Ad unit from BannerExchange.net
TextExchange.net - Exchange text based ads with other websites that are similar to those used with Google Adwords/Google Adsense. Ad units are fully customizable to better fit your website and can display 2 to 3 ads per unit. This free advertising network has an affiliate program so that members can earn additional text ad impressions.
Below is an Example of a Horizontal Ad unit displaying 2 Ads from TextExchange.net