Think before linking your sites together

Lets say you have invested plently of time and money developing a number of sites and you are making money from search engine traffic.

The worst thing that can happen is if Google throws all of your sites out of the serps in one feld swoop.

One way to increase the chances of this happening is to link all of your sites to each other. Sitewide links may be more of a problem.

I'm not saying that you should never link your sites, just be strategic about it. If the purpose for the link is to move visitors, use nofollow.

If you are trying to flow pagerank, flowchart the links and avoid circular patterns. You can link them one way all in a row:

A to B
B to C
C to D etc.

If you have one site that you want to focus PR on then point all sites to that one site w/o pointing back. The pointing sites should not link to each other.

Other things to consider are if all of your sites are on the same server/IP, on the same C class IP, or have adsense on them with the same account.

How do you link your sites together or do you avoid this all together?