there are tons but whatever you do use smaller faster defensive linemen to challange them they certianly wont like being beat by the smaller guy's and will begin to give more in the drills also have them pull and trap it will take more effort and there footwork will improve with the added challenge

Like Toby said there's differant ways, most can be had in a good line men book..
Off hand I just can't come up with one but I'm sure there out there... Now that being said most of my coaching was with the back's but as a head coach for some years in youth football I did have some say with the line ... Two things that was a must was a proper stance and knowing the count and taking off on that count... What these mean is this ... I don't like a lazy stance, which means I don't let them have their free arm laid across their lap and leaning on it, which I see everywhere... That's just pure lazy... I want that hand in a fist at or around their knee ready to fire ... Second, Don't use the whistle so much ... That's a lazy coach... It may take more time during drills and all but I believe it will pay off in the long run... Just one more thing ... I reward my line men much more than in years past and they know it ... Have them want to play for ya and keep the fire going with them at all time's .. They will try to challenge you with this but get to know them,share with them and let everyone involved understand that we go no where without them ... Just look at the BEARS lol