Change links to commercial traffic between your sites and NOT for search engine rankings. The top lists are a good example of this type of exchange. It allows you to trade traffic with thousands of affiliates. Trade exchanges are also a great way to place ads on other sites without having to pay a penny. This can be an excellent public relationship for a new non-adult business or for a more industry-related service. The trades do as well as you. They are not traffic wells, they are what they are: another way to get to the table.
If you build free sites, you will be able to get traffic from commercial traffic. PlugRush is a well known example of commercial link site and there are many other sites like this on the net. Once you've built a site, you submit it to those sites, and if your site meets the requirements of each list you have, then they can include your site in their lists.
It is very easy to set up the transaction, you just need to add the script to your site. The more visitors you visit, the more traffic you will get on your site.