I just put a car up for sale on autotrader.com...and it turns out that
companies start spamming you (without consent and not autotrader's
fault) about the car and other non-car related services. certainly a
nuisance, but here's where google voice rocks. I can immediately block
those callers and they'll receive "not in service" responses next time
they try to call. I never fear giving out my google voice number
because of this feature (and others)...also love the free text
messaging, too.