Automatic linking in wordpress?

I'm setting up a small blog farm. I want a plugin that can automatically create backlinks within new posts based on specific keywords.

For example..If a new post gets created and it has the keyword "acai berry" the plugin automatically creates a link to my website using that as anchor.

I had seen a similar plugin ..but I can't seem to find it.

Grab Max Blog Press Ninja Affiliate, it's designed to turn keywords in to affiliate links but i also use it for regular links for SEO. You can control maximum keywords to convert per post so it doesn't look spammy and a bunch of other stuff.

Im checking it out.... Curious though... Im thinking of going with multiple C class IPS and then setting up auto blogs on them to link to my main site. What approach do you use?.. I was just wondering if free hosts would be a more easier and of course cheap solution.