I really like CBSSports's Rapid Reports. If you haven't checked them out I recommend them. It's a really good way to follow practices.
Also, EA Sports has posted some videos of the rookies doing drills for Madden NFL 10.
DetNews.com - Martin Mayhew thrilled with play of QBs
MLive.com - Detroit Lions offensive line gives backs room to run
MLive.com - Lions' Martin Mayhew pleased with quarterbacks
EA Sports - Madden NFL 10 Rookie Ratings Drills