I think linking them in the niche works well although I have been know to link a few of my other non-related sites as well. I think it helps with traffic and like you said, they may interested once they click the link.
Nah, just don't go crazy with it.
FYI, a big SEO company I use to work with, 2 major strategies were:
Building links from their owns sites.
I think linking within sites of the same niche or theme on the same server is OK. It is just like "internal linking" among 1 single site.
I myself do this and get no penalties up to now.
It is fine to link if the reasons behind it are correct. Always ask yourself - would I be happy explaining to Google (and co) why I'm linking to this site. Unless you're just trying to trick them then it's fine. Don't be scared to link!
Have a look at larger publishers, such as newspaper and magazine publishers, multinationals, etc. Many of them link between all their sites (often from all pages) thus creating thousands of links. If you have lots of quality incoming links to all of your sites from outside (like those big publishers have), then there is no problem. If you have few links from the outside then it is a problem. What is a "good" and what is a "bad" linking pattern is a gliding scale, so it is hard to say at which point it will turn against you.
Having bought a good number of domains and cross-linking I have had nothing but success doing it. Just be careful and where possible make sure they are related in some way.
Our company sites have millions of pages and nearly all of them have a nav bar that links each page to the home pages of all these sites. It made me nervous when I joined two years ago, but I can see that these links benefit users and noticed no penalty.
The problem is when a third-party site gives you run-of-site links - that looks purchased, hence a penalty isn't far away.
Hmmm .... make me nervous too.
We just delinked sites in our network to see if anything happened following a number of strong advices from some webmasters . Words like "link farm" were enough to have rel="nofollow" applied.
ROS links are fairly common. Many bloggers have a "favorite sites" section where they share links to sites they feel are authoritative. Think of bloggers who have ROS links to WebmasterWorld or other similar sites. Automating the penalization of that could possibly cause collateral damage to authoritative sites.
The only time I have personally witnessed a penalty for interlinking involved a site with hundreds of "sister" sites all in the same niche. It had something to do with a certain topic. So they had a main topic site, but they had other sites built around keywords related to other types of related topics. They'd been hit with a penalty and we're wondering why. So they contacted me because they wanted to hire me to help them. I talked to them for a half hour and from what they told me it seemed that was the problem so I told them what to do to fix it. I don't think they ever thanked me but they used my advice and got unbanned.
What about if it influences ranking ?
"Favorite websites" is a legitimate vote. It should definitely influence ranking. Because it's run of site doesn't mean it should influence ranking more and I think most people agree it does not.
ROS [ run of site ] - do you mean "random links " here and there ? If so i see no harm.
But , more elaborate "link farms" without no follow are a big risk in my view.
[edited by: Whitey at 11:32 am (utc) on Mar. 1, 2009]
This topic has come in really handy for me. I launched a new website a few weeks ago and have been ever so scared of linking to it from my main site.
The two sites deal with products that are distinct from one another yet share a common creation process; So therefore they are somewhat related.
On my main site I review some of the work I have I have performed for my clients. I wonder, if rather than just placing a link with some anchor text from my manin site to the new site I could write an article about the new website and devote an entire page with a link?
Yes, you can link from one site to another (yours). You can drive traffic to new sites this way.
Still, Google identifies the IP (if the sites are running on a shared server) and that doesn't count too much or at least with the same weight as if they were non related.
In a short way, G knows both sites are "brothers" (or cousins) and that is not a natural link.