A High Rankings Forum member talks about how he has a variety of sites that are all networked on the same server with the same owner. They're not related topically, but there are some subpages where adding links may be of value to search engines and visitors. Would it be bad to link to pages in the same link network? Are there any risks?
It depends, actually. If you're trying to hide the relationship between sites, as one says, it's deceptive and could be dangerous. On the other hand, if you're being open about the relationship and linking where appropriate, it should be fine.
Another option is to add "our link network" to the footer of the site to bring other people to your other pages. It's not as topical, but it may drive traffic. However, that may not necessarily be the kind of traffic or links you're aiming for, so that is totally up to you.
The forum discussion that ensues is informative, so take a read at High Rankings Forum.