I just received a request from someone for a link through one of our affiliate sites - this is not uncommon - but the interesting thing is that his approach was to build a triangle link. One of his sites links to one of my sites and I link back to a different site he owns in the same genre. This is smart as search engines are devaluing straight link exchanges as they are too easy to acquire and not “natural”. Here are some advantages and disadvantages as I see it on the triangle links:

The triangle link exchange has the following advantages:
1) It’s not a direct exchange (so it seems more natural),
2) They are manageable - you can go out and ask for them in tit-for-tat manner
3) You can set the anchor text (to more closely resemble a natural link)

Disadvantages of triangle linking:
1) Still takes time to build and manage
2) Long term, search engines will figure these out and de-value
3) The links are still primarily on a link page as part of an exchange and not built into relevant content.

Anyhow, intereting approach that is worth testing.