Where do you get your permanent unique backlinks? I have used a couple of websites for baclinks but due to the high ammount of recent posts they get, its hard keeping the backlinks alive. I have also used a couple of blogs, they do have backlinks enabled but it doesnt stay unique for more than a day due to a lot of comments.
Look at buying a spot on a high PR blog, preferably in the sites blogroll. Make sure the blog has a decent about of posts or has a growing number of posts.