I hear you want to exchange links with other PR sites, and then I hear.. NO! Google hates links exchanges.. Focus on content.. Should I be trying to exchange links??
Too many link exchanges is a sign that Google see your site as not exactly a valuable good content site. Google values link exchange only on related sites. Linking out to irrelevant domains will not likely to help the site visitors, and Google knows this. According to Google, one way links are the best. Always aim for writing very useful and good content for your visitors, because this can earn links you will not even know they are linking to you. THese organic links are what makes sites rank, and this what make Google hates link exchanges, because in most link exchange, quality content and relevance is not even included in the criteria of site selection. What hurts to Google is that, there are sites that solely depend on page rank during their link exchange process, and as a penalty, Google stripped the PR of these sites, which we have observed in most directories in the past months, being their PR devalued. My advice: Write a really useful and unique content, limit your link exchange only on highly related and expert sites, write content in a periodic basis. And link baiting that gets organic links will take care of the rest.