If you are a regular traveler, I recommend renewing it so your passport is valid for another 10 years. But if you're not a frequent traveler, I wouldn't worry about 6 month validity. I've traveled with 3 months validity and have not encountered any problems. The US has reciprocal agreements with several countries that automatically extend the life of a passport for another six months. The effect is you can use your passport until it's expiration date (but not beyond):
http://www.state.gov/documents/organization/104770.pdf