Here is a link to the projected compensatory picks for the 2009 draft, based on 2008 FA. He has done a great job with his projections, especially the last couple of years. I typically use them when I'm looking at how the draft may shake out early on. The real comp picks will be announced around the 22nd or 23rd of March -- til then, this article gives you a good rule of thumb to go by.
As you can see, he projects Detroit getting two late 7th rounders. Not much, but hey -- couple good picks to take fliers on positions of need -- say returner? -- or for depth at spots like TE?