Epupz is a handy site too.
i breed shar-pei puppies and the main sites i use are
epupz.
k9 puppy.
pets4homes
just a word of warning.
do your homework on the breed of dog, as hereditary illness are very common with some breeds.
also make sure parents have had the relevant tests, and are clear and view these.
dont be afraid to ask "awkward" questions eg.
if they are KC reg, ask to look at the dams papers. and expect to get the puppies KC papers on collection of puppy.
also look at the conditions the puppy has been reared. have they been reared indoors? and is the house clean

just trust your instincts.
have they been vet checked and has the puppy recieved their first vaccination. there will be a record of this. they get this at around 6 weeks old.
make sure your house is puppy proof before bring it home
also a good tip is to supply the breeder with a puppy blanket before collection of the puppy.
then ask the breeder to place this in the cage with the puppies the day before collection.
when you bring it home, your house will be strange to it, and if you place this blanket in its bed, it acts as a comforter to it.
also make sure you use the same brand of food the breeder has been feeding the puppy.
i am going on a bit, but you would not believe the questions i have been asked over the years.