If he is only 8 weeks old, he may be nipping until he is about 18 - 20 weeks old

so it does take time and patience and sometimes it can seem as if you are getting nowhere fast! ;)
It sounds a little to me, as if he may just be getting very excitable and playing - pups often do this, and it just takes time and patience. You may want to also put him out the room for a couple of minutes, or go out yourselves, as this can help when he bites. If you yelp, make sure it is slightly scary or as if you are really inpain, or he may think you are just a new squeaky toy LOL!
How about getting a copy of "The Perfect Puppy" by Gwen Bailey? Its very good.
Lindsay