Lately there has been a large spread of websites that act as intermediaries for link exchange, and websites that offer link exchange with their portfolio of websites  (this means that they offer an entire webpage with a link directory and you need to introduce it in your website). Do these websites help? The answer is NO and I will try to give you some of the reasons for this.

1.  Fist of all who will collaborate with a website that intermediates link exchange will not trade one link but hundreds or maybe thousands of links which will be added most probably in a page that will be named links, partners or any other name. So there will be this page that will contain hundreds or thousands of links … and among those links you will have your link.  From the start the Google-bots will see that this page is destined just for links, without any rules (same category, same language) so the links are artificial (they don't represent a trust worthy reference) and will be ignored or even worst this might bring upon the cancellation of links that have been already considered as valid back-links. So the result is far from being in your favor.

  There also is a possibility for the link towards your website to be included by the "exchange partners" in a webpage with any name….lets say page.html, this page may not have any link with the website so the Google-bot will never reach the page because he doesn't know that page exists.

2. Those who will participate in programs that consist of introducing in their website a whole page of links (and this is what such programs require) must acknowledge that this procedure is considered as being a link-farm (A link farm is a form of spamming the index of a search engine); this means disaster because besides of the risk that this procedure will not help in any way you might be banned from the search engines` systems. 

3. Google from it's beginnings used as basis for the determining the relevance of a website for a certain word the system of the indexed back-links (these being considered as recommendations made by one website for another website), thus the more recommendations (back-links) one website has the more important it becomes. In order to avoid the indexing of artificial reciprocal links that are considered as poisoning, lately Google has adopted a series of measures meant to detect this kind of links.

Some of these measures are:

-      No indexation for the links that are generated from a single page that contains numerous external links (generally more than 10).

-     Tacking into consideration only the links that are generated from a webpage as a recommendation, from sites in the same domain or in domains closely related, web pages written in the same language or from the same geographical region.

For example we have a website that sells auto parts with 3 links to: a website that sells cars, a financing website and to a website with gardening products. Google will ignore the link towards the gardening website in 80% of the cases.

The distinction between the domains of activity, geographical regions, etc is made by Google mostly with the help of dmoz.org