plugin or place to hack for internal keyword linking?

I use autolinks for automated external links, and it works beautifully. But now I find I need to implement internal keyword linking as well, using a separate set of keywords. I can’t do this with autolinks, because I need those external links to have “_blank” attached so they open into a new window. (Or maybe I could .. by hacking the plugin to recognize internal links by the domain and leaving off the _”blank.” Hmmm).

Anyhow, this seems like a common problem and I wondered how others have solved it.

Thanks for your thoughts …