My personal opinion is that back linking should be done manually without the help of any software.

Right now, I am having the most SEO success with just pounding the pavement and finding other related sites that I can write content for. Then contact the site owners and offer some content in exchange for a link. A few good relevant contextual links from some authority sites obtained this way has done a lot more for my sites than using any of the automated tools out there now.

Not saying that the automated stuff doesn't work -- just wanted to mention another perspective.