I have a big site which allows me to test alot of different SEO methods to rank inner pages. Seems like throwing 20 to 30 article directory links does nothing to affect the serps now. A very similiar page gets 30 in-content links from a private blog network and I'm seeing serious movement. Seems to me like the big directories like articesbase, upublish, amazines, etc. are worthless in terms of SEO. The popularity of private link networks are rising as links from there actually do work. My concern with these networks is that they can easily be de-indexed/de-valued by Google as it would take a manual reviewer only a few minutes to figure it out. Looks like a few big networks have gone down recently. What have your experiences been?