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I highly recommend caution on exchanging links. While this was the big thing a few years ago, the Google algorithms are much more intelligent now. You can actually be penalized for having links to your site from other sites where the topic doesn't relate to your site, or from sites that seem to be focused on non-content focused things. We get a lot of requests from people to remove links for just this reason.
If you decide to trade links anyway, you should make sure the person linking to you does not add "rel=nofollow" to their link. If they do this, they basically negate any search engine value they are giving you.
Additionally, if you exchange links, you'll want to look at your page rank. While the search engines don't necessarily treat pagerank as important as they used to, if your pagerank is substantially higher than the person you are trading with, then your link to them will be substantially more valuable. A sit like this one (WebDeveloper) has a page rank 6, which is worth a lot more than sites with ranks of 1 or 2.
Of course, knowing our rank here is a 6, you might be tempted to put your links into posts here to get the backlink. If you do this, know that we use the rel=nofollow, so you'll get no search engine value from it. Having your links on this site without the nofollow would potentially hurt our standing.
Bottom line - be careful with how you play with links. They have the potential to hurt you as much as hlep you. SEO isn't as simple as it used to be!