I passed today. I will list my study materials, however I SUGGEST taking the BIOLOGY CLEP FIRST before sitting the NS exam. I say this as the NS exam is made up of 50% of biology and the balance of chemistry, geology, physics, and astronomy. If you can pass biology first then the NS exam isn't so bad. I studied for biology for 3 weeks took the exam and passed. Then I added another 2 weeks of study for the NS exam and passed it too.
Here is my list:
INSTANTCERT - Biology
REA Biology
Standard Deviants - Biology
www.DavidandLaurie.com - NS exam study guide.
BTW: InstantCert does have 123 science questions listed in the GED Science section that can be somewhat helpful.
GOOD LUCK!!!!!