 To my knowledge there are two types of textads:1. Targeted ads such as google adsense 2. Text ads that are sold to the highest bidders #1 is very frequently used on top sites and is a great way to go. Google (or whomever you use) serves up the ads based on some proprietary algorithm that determines the most suitable ads based on your page's content. You get paid anywhere from a few cents to a few dollars (if you're very lucky) per click. #2 requires work on your part and if you have a good pagerank can help the advertised site raise their own pagerank. Unless you abuse them, they do nothing negative to your site. | 
