Here are my thoughts about Blog Networks.
1. If you want to give exposure to your writing talents, Blog Networks would be good. You would also drive traffic from Blog Networks directly to your sites via embedded anchor texts.
2. If you plan to use Blog Networks as a tool to drive Search Engine Traffic, improve Search Engine Results Positions or raise your Page Ranks, then you need to think again
Based on what I read so far, I can sum up that all these Blog...