During the bye week, the Detroit Lions brought in 24 players for workouts, and ended up signing two of the biggest names on their list.
First they signed former Cowboys OL Leonard Davis. According to Pride of Detroit, the Lions brought Davis in for a workout back in August, but only after this second workout did they sign him. Also, Davis gives their interior line some needed depth. My guess is that he wasn't in the greatest shape back in August, and he's improved himself since then.
None of these are panic moves, but it shows that the Lions know they can make their team better. And that even players who haven't been able to find work for the past couple months can help them.