Just do not do 100 outbound links from the home page of a single site. That would be way too many links. I would limit it to perhaps 5.
You might get into trouble with G by linking out to unrelated sites. Matt Cuts has used an example of a site whose rankings dropped because the site contained footer links that linked to a ring tones site, but those were sitewide links. That is also the problem with exchanging links with unrelated sites. They do not look natural. A smarter way to do it would be to use a tech site for tech links, automotive site for automotive links, recipe site for recipe links, etc.
It may be difficult to make it look like these are not paid links. Penguin puts much more focus on stand-alone links in a footer or sidebar.
Make sure that you never expose the domains of the site where you provide the links.
Be aware that if you are reported, Google may infiltrate the network to find out how many sites are part of the network. That is how Build My Rank appears to have been taken down by Google. They can also determine who owns the sites through domain registrations. Google is a registrar, so private registrations will probably not deter them. I think they have access to the raw WHOIS data. Why else would they become a registrar when they do not sell domain registrations?
There would have to be a lot of potential profit in this plan before I would touch it. There is too much downside risk to do it for free.
Remember, Google is not a democracy. You are declared guilty until you can figure out what you are guilty of. If they do not like what you are doing, they could go after all of your sites, and they have done that many times in the past. You would need to go to great lengths to isolate these sites from your other sites.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin