Have you guys seen this article on cnn.com about link exchanges? http://www.cnn.com/2009/TECH/07/14/cnet.google.link.exchange/index.html Do you agree with their conclusion that link exchanges can help your page rank as long as you follow some simple rules (exchange links with similar topics, dont pay for links, dont link to bad neighborhoods)?
Why would i want to exchange links, when i can get oneway backlinks for free? You just need to know where to look. Personally i don't exchange links on any of my websites, i sell them, because thats far more profitable.
Google has a few filters that can ruin your site you done by non-professional, like Google Bombing filter...