Globetrotter - 12:27 pm on Sep 19, 2010 (gmt 0)
I've done this, but so far I've replaced to much links at the same time so it doesn't look natural. Now I'm changing the algorithm to maximize the number of links in total and per keyword. It did help me and my visitors to get related content.
So far it didn't harm my site, maybe it did harm the keyword but because this is the first test I'm not sure about that.