Hey, I just wondered, I have about 14 sites and I have a habbit of interlinking them all with footer links to each other. What damage could this be doing if any?
This can be considered a link scheme. http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=66356
Worst case scenario is that the search engines would think they're a link farm and would de-list all of them (ie: ban them) from their indexes. However, I'd need to know WHICH sites they are to be able to better determine the likely outcome.
Yes, link exchanges can still be used just don't exchange links such as 20 links at a time and fill pages with links. If you do it responsibly and link with quality sites you should not have a problem. Remember tho if you do a link exchange then make sure that the website is a quality website because google will look at it as you condoning anything they put on their website.
The first question is whether or not the sites are related topically. If you did not own all of them, would there be any natural reason for them to link to each other? I have heard folks come down on both sides of this as excessive linking. I think as long as the sites are related topically you should have no trouble. I do, however, think 14 footer links is a bit excessive from a usability standpoint as well as an SEO standpoint.
Unless they're super relevant (all your sites inter-linking eachother) don't worry about. Obviously, people won't click irrelivant links, and backlinks from the same I.P/server are diminished in quality than from others anyway.